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1.  Activation of cholinergic receptors blocks non-adrenergic non-cholinergic contractions in the rat urinary bladder 
Brain research bulletin  2008;77(6):420-426.
In the present study, the plasticity of the non-adrenergic non-cholinergic (NANC) response was investigated. Isolated rat bladder strips were electrically stimulated and the evoked contractions were isometrically recorded. The NANC part of the contractions were unmasked by applying 500 nM 4-DAMP, a potent muscarinic antagonist. Treatment of the bladder strips with 10 μM carbachol (a cholinergic agonist) increased the muscle tone but did not alter the neurally evoked contractions. However, carbachol decreased: (1) the NANC response from 74.6% to 33.3% of control and (2) the purinergic contractile response to α,β methylene ATP (α,β mATP) (10 μM) from 97.0% to 43.4% (p<0.05). Treatment with the cholinesterase inhibitor eserine (10 μM) also significantly decreased the NANC response to 21.1% (p<0.0001). The purinergic receptor antagonist suramin (100μM) did not affect the neurally evoked contractions, however; subsequent addition of 4-DAMP decreased the contractions to 31%. Activation of the smooth muscle cholinergic receptors (with carbachol or eserine) and purinergic receptors (with α,β mATP) decreased the NANC contractions and the direct contractile response to α,β mATP. When the electrically evoked contractions were facilitated by the L-type Ca2+ channel activator, Bay-K 8644 the subsequent application of 4-DAMP did not unmask inhibited NANC contractions. We conclude that activation of muscarinic receptors by cholinergic agonist, carbachol or by endogenous acetylcholine (ACh) induce a cascade of events that leads to diminished purinergic response and consequently an inhibition of the bladder NANC response.
PMCID: PMC2724651  PMID: 18755252
nicotinic acetylcholine receptors; muscarinic acetylcholine receptors; P2X purinergic receptors; non-adrenergic, non-cholinergic (NANC) contractions; receptor interaction; bladder smooth muscle; bladder contractility
2.  Adenosine Actions are Preserved in Corpus Cavernosum from Obese and Type II Diabetic db/db Mouse 
The journal of sexual medicine  2008;5(5):1156-1166.
Erectile dysfunction (ED) in diabetes is associated with autonomic neuropathy and endothelial dysfunction. Whereas the nonadrenergic-noncholinergic (NANC)/neurogenic nitric oxide pathway has received great attention in diabetes-associated ED, few studies have addressed sympathetic overactivity.
To test the hypothesis that adenosine-induced inhibition of adrenergic-mediated contractile responses in mouse corpus cavernosum is impaired in the presence of diabetes.
The db/db (obesity and type II diabetes caused by a leptin receptor mutation) mouse strain was used as a model of obesity and type II diabetes, and standard procedures were performed to evaluate functional cavernosal responses.
Main Outcome Measures
Increased cavernosal responses to sympathetic stimulation in db/db mice are not associated with impaired prejunctional actions of adenosine.
Electrical field stimulation (EFS)-, but not phenylephrine (PE)-, induced contractions are enhanced in cavernosal strips from db/db mice in comparison with those from lean littermates. Direct effects of adenosine, 2-chloro-adenosine, A1 receptor agonist C-8031 (N6 cyclopentyladenosine), and sodium nitroprusside are similar between the strips from lean and db/db mice, whereas relaxant responses to acetylcholine and NANC stimulation are significantly impaired in the cavernosal strips from db/db mice. 5′-Iodotubercidin (adenosine kinase inhibitor) and dipyridamole (inhibitor of adenosine transport), as well as the A1 agonist C-8031, significantly and similarly inhibit contractions induced by stimulation of adrenergic nerves in the cavernosal strips from lean and db/db mice.
Results from this study suggest that corpora cavernosa from obese and diabetic db/db mice display altered neural-mediated responses that would favor penile detumescence, i.e., increased contractile response to adrenergic nerve stimulation and decreased relaxant responses upon activation of NANC nerves. However, increased cavernosal responses to adrenergic nerve stimulation are not due to impaired negative modulation of sympathetic neurotransmission by adenosine in this diabetic model.
PMCID: PMC3016713  PMID: 18221284
Adenosine; Obesity; Diabetes; Sympathetic Neurotransmission; Animal Models
3.  Diabetic plasticity of non-adrenergic non-cholinergic and P2X-mediated rat bladder contractions 
Brain research bulletin  2013;95:40-45.
We investigated the plasticity effects of diabetes mellitus and diuresis on the non-adrenergic non-cholinergic (NANC) and purinergic (P2X-type) contractile responses in longitudinal rat bladder strips. Female Sprague-Dawley rats received streptozotocin to induce diabetes, or sucrose in water to induce diuresis as a control condition for polyuria. Experiments were carried out at four weeks after treatments, using bladders from not-treated rats as control. Urinary bladder strips were electrically stimulated throughout the experiments to generate neurally evoked contractions (NEC). In all cases, P2X-mediated purinergic contractions were evaluated at the beginning and end of the stimulations with α,β-Methylene Adenosine Triphosphate (α,βMeATP). The NANC responses were assessed by using two independent protocols. First, cholinergic receptors were activated with carbachol (CCh), followed by inhibition of the muscarinic component with atropine. In the second protocol, the application order for CCh and atropine was reversed. The NANC response, unmasked with the application of atropine, and the P2X purinergic contractions were analyzed. NANC contractions in diabetic bladder strips are more resistant to the desensitizing effects caused by activation of cholinergic receptors. In early stages of experimental diabetes, NANC responses in diabetic strips are less sensitive to functional inhibition mediated by the cholinergic activation. However, P2X-mediated purinergic contractions are more sensitive to desensitization in diabetic or diuretic bladders. For instance preventing muscarinic receptor activation with atropine does not counteract the desensitization of purinergic contractions in either diabetic or diuretic strips. We suggest that diabetes may induce a plasticity of the NANC and P2X-mediated bladder contractile responses. The first one may be associated with diabetic neuropathic damage to bladder nerves, while impaired P2X purinergic contractions might be associated with detrusor hypertrophy observed in diabetic and diuretic strips.
PMCID: PMC3681287  PMID: 23562604
Diabetic bladder dysfunction; purinergic receptor; cholinergic receptor; non-adrenergic non-cholinergic response; neurally evoked contraction; detrusor muscle
4.  Non-adrenergic non-cholinergic inhibitory innervation shown by electrical field stimulation of isolated strips of human gall bladder muscle. 
Gut  1994;35(3):412-416.
Non-adrenergic non-cholinergic (NANC) inhibitory nerves have been described in all regions of the gastrointestinal tract, but have not been shown previously in the human gall bladder. Electrical field stimulation was used in the presence of various agonists and antagonists to show NANC inhibitory innervation in strips of human gall bladder muscle. Gall bladder strips were set up isometrically in an organ bath containing oxygenated Krebs's solution. Electrical field stimulation was applied at 10 Hz, pulse width 0.3 ms and supramaximal voltage at intervals of 3 to 5 minutes. Of 60 strips that contracted in response to electrical field stimulation, 30 showed relaxation on electrical field stimulation in the presence of either carbachol (5-10 microM) or else atropine (0.5-2 microM) plus cholecystokinin octapeptide (0.01-0.1 microM) or caerulein (0.1 nM) or histamine (5-10 microM). In 22 strips this relaxation was not abolished by guanethidine (2-5 microM) showing the NANC nature of this response. The NANC relaxation was abolished by L-nitroarginine (100 microM) and this effect was partly reversible by L arginine (200 microM). All responses to electrical field stimulation were abolished by tetrodotoxin (0.2-2 microM). These results show for the first time a NANC inhibitory innervation in human gall bladder muscle. The probable neurotransmitter is nitric oxide.
PMCID: PMC1374601  PMID: 8150357
Age-related changes in non-adrenergic, non-cholinergic (NANC) neurotransmission might contribute to differences in gastrointestinal motility. Our aim was to determine age-related changes in functional innervation with vasoactive intestinal polypeptide (VIP) and substance P (Sub P) in rat jejunum. We hypothesized that maturation causes changes in neurotransmission with these two neuropeptides. Longitudinal and circular jejunal muscle strips from young (3 months) and middle-aged (15 months) rats (total: 24 rats) were studied; the response to exogenous VIP and Sub P and the effect of their endogenous release from the enteric nervous system during electrical field stimulation (EFS) were evaluated. In longitudinal muscle, response to exogenous VIP and endogenously released VIP during EFS were increased in middle-aged rats, while the effect of endogenously released Sub P was decreased. In the circular muscle, the response to endogenously released VIP was increased in middle-aged rats, while the effects of exogenous VIP and endogenously released Sub P were unchanged. Response to exogenous Sub P was unaffected by maturation in both muscle layers. Spontaneous contractile activity was increased in the longitudinal and circular muscle of the older rats. In the jejunum of middle-aged rats, participation of VIP in functional NANC innervation was increased, while functional innervation with Sub P was decreased. These changes in the balance of inhibitory and excitatory neurotransmission occur during the year of maturation in rats and demonstrate an age-dependant plasticity of neuromuscular bowel function.
PMCID: PMC2783308  PMID: 19734110
Aging; enteric nervous system; maturation; motility; small intestine; substance P; vasoactive intestinal polypeptide
6.  Effect of chronic, extrinsic denervation on functional NANC innervation with vasoactive intestinal polypeptide and substance P in longitudinal muscle of rat jejunum1 
Intestinal denervation contributes to enteric motor dysfunction after intestinal transplantation [small bowel transplantation (SBT)]. Our aim was to determine long-term effects of extrinsic denervation on functional non-adrenergic, non-cholinergic innervation with vasoactive intestinal polypeptide (VIP) and substance P. Contractile activity of jejunal longitudinal muscle from six age-matched, naïve control rats (NC) and eight rats 1 year after syngeneic SBT were studied in tissue chambers. Spontaneous contractile activity did not differ between groups. Exogenous VIP inhibited contractile activity dose-dependently in both groups, greater in NC than in SBT. The VIP antagonist ([D-p-Cl-Phe6,Leu17]-VIP) and the nitric oxide synthase inhibitor L-NG-nitro arginine prevented inhibition by exogenous VIP and electrical field stimulation (EFS) in both groups. Exogenous substance P increased contractile activity dose-dependently, greater in NC than in SBT. The substance P antagonist ([D-Pro2,D-Trp7,9]-substance P) inhibited effects of exogenous substance P and increased the EFS-induced inhibitory response. Immunohistofluorescence showed staining for tyrosine hydroxylase in the jejunoileum 1 year after SBT suggesting sympathetic reinnervation. In rat jejunal longitudinal muscle after chronic denervation, response to exogenous VIP and substance P is decreased, while endogenous release of both neurotransmitters is preserved. These alterations in excitatory and inhibitory pathways occur despite extrinsic reinnervation and might contribute to enteric motor dysfunction after SBT.
PMCID: PMC2561234  PMID: 17971029
enteric nervous system; extrinsic denervation; motility; small intestine; substance P; vasoactive intestinal polypeptide
7.  Cannabinoids and the gastrointestinal tract 
Gut  2001;48(6):859-867.
The enteric nervous system of several species, including the mouse, rat, guinea pig and humans, contains cannabinoid CB1 receptors that depress gastrointestinal motility, mainly by inhibiting ongoing contractile transmitter release. Signs of this depressant effect are, in the whole organism, delayed gastric emptying and inhibition of the transit of non-absorbable markers through the small intestine and, in isolated strips of ileal tissue, inhibition of evoked acetylcholine release, peristalsis, and cholinergic and non-adrenergic non-cholinergic (NANC) contractions of longitudinal or circular smooth muscle. These are contractions evoked electrically or by agents that are thought to stimulate contractile transmitter release either in tissue taken from morphine pretreated animals (naloxone) or in unpretreated tissue (γ-aminobutyric acid and 5-hydroxytryptamine). The inhibitory effects of cannabinoid receptor agonists on gastric emptying and intestinal transit are mediated to some extent by CB1 receptors in the brain as well as by enteric CB1 receptors. Gastric acid secretion is also inhibited in response to CB1 receptor activation, although the detailed underlying mechanism has yet to be elucidated. Cannabinoid receptor agonists delay gastric emptying in humans as well as in rodents and probably also inhibit human gastric acid secretion. Cannabinoid pretreatment induces tolerance to the inhibitory effects of cannabinoid receptor agonists on gastrointestinal motility. Findings that the CB1 selective antagonist/inverse agonist SR141716A produces in vivo and in vitro signs of increased motility of rodent small intestine probably reflect the presence in the enteric nervous system of a population of CB1 receptors that are precoupled to their effector mechanisms. SR141716A has been reported not to behave in this manner in the myenteric plexus-longitudinal muscle preparation (MPLM) of human ileum unless this has first been rendered cannabinoid tolerant. Nor has it been found to induce "withdrawal" contractions in cannabinoid tolerant guinea pig ileal MPLM. Further research is required to investigate the role both of endogenous cannabinoid receptor agonists and of non-CB1 cannabinoid receptors in the gastrointestinal tract. The extent to which the effects on gastrointestinal function of cannabinoid receptor agonists or antagonists/inverse agonists can be exploited therapeutically has yet to be investigated as has the extent to which these drugs can provoke unwanted effects in the gastrointestinal tract when used for other therapeutic purposes.

PMCID: PMC1728337  PMID: 11358910
8.  Umbilical artery tone in maternal obesity 
The increasing prevalence of obesity constitutes a major health problem in obstetrics with implications for feto-maternal growth and wellbeing. This study investigated and compared the contractile properties of umbilical arteries excised from obese women, with those excised from women with a normal body mass index (BMI).
Sections of umbilical artery were obtained from umbilical cord samples immediately after delivery and mounted for isometric recording in organ tissue baths under physiological conditions. Cumulative additions of 5-Hydroxytryptamine (5-HT) and Prostaglandin F-2alpha (PgF2alpha) were added in the concentration range of 1 nmol/L to 10 micromol/L. Control vessels were exposed to Krebs physiological salt solution (PSS) only. The resultant effects of each drug addition were measured using the Powerlab hardware unit.
5-HT exerted a significant effect on human umbilical artery tone at concentrations of 100 nmol/L, 1 micromol/L, and 10 micromol/L in normal (n = 5; P < 0.05) and obese (n = 5; P < 0.05) women. The contractile effect was significantly greater in vessels from obese women {Mean Maximum Tension (MMT) = 4.2532 g} than in those from women of normal BMI (MMT = 2.97 g; P < 0.05). PgF2alpha exerted a significant contractile effect on vessels at 1 micromol/L and 10 micromol/L concentrations when compared with controls (n = 5; P < 0.05). There was a non-significant trend towards an enhanced tone response in vessels from obese women (MMT = 3.02 g; n = 5), in comparison to vessels from women of a normal BMI (MMT = 2.358 g; n = 5; P > 0.05).
These findings support the hypothesis that endogenous regulation of umbilical artery tone is altered in association with maternal obesity. This may be linked to the cardiovascular effects of secretory products of adipose tissue, with implications for the feto-maternal circulation.
PMCID: PMC2649927  PMID: 19161625
9.  Increased cholinergic contractions of jejunal smooth muscle caused by a high cholesterol diet are prevented by the 5-HT4 agonist – tegaserod 
Excess cholesterol in bile and in blood is a major risk factor for the respective development of gallbladder disease and atherosclerosis. This lipid in excess negatively impacts the functioning of other smooth muscles, including the intestine. Serotonin is an important mediator of the contractile responses of the small intestine. Drugs targeting the serotonin receptor are used as prokinetic agents to manage intestinal motor disorders, in particular irritable bowel syndrome. Thus, tegaserod, acting on 5-HT4 receptor, ideally should obviate detrimental effects of excessive cholesterol on gastrointestinal smooth muscle. In this study we examined the effect of tegaserod on cholesterol-induced changes in the contractile responses of intestinal smooth muscle.
The effects of a high cholesterol (1%) diet on the in vitro contractile responses of jejunal longitudinal smooth muscle from Richardson ground squirrels to the cholinergic agonist carbachol were examined in the presence or absence of tetrodrodotoxin (TTX). Two groups of animals, fed either low (0.03%) or high cholesterol rat chow diet, were further divided into two subgroups and treated for 28 days with either vehicle or tegaserod.
The high cholesterol diet increased, by nearly 2-fold, contractions of the jejunal longitudinal smooth muscle elicited by carbachol. These cholinergic contractions were mediated by muscarinic receptors since they were blocked by scopolamine, a muscarinic receptor antagonist, but not by the nicotinic receptor antagonist, hexamethonium. Tegaserod treatment, which did not affect cholinergic contractions of tissues from low cholesterol fed animals, abrogated the increase caused by the high cholesterol diet. With low cholesterol diet TTX enhanced carbachol-evoked contractions, whereas this action potential blocker did not affect the augmented cholinergic contractions seen with tissues from animals on the high cholesterol diet. Tegaserod-treatment removed the effects of a high cholesterol diet on neuronal muscarinic receptors, as the potentiating effect of TTX on carbachol-elicited contractions was maintained in these animals.
A high cholesterol diet causes significant changes to cholinergic neurotransmission in the enteric nerves of the jejunum. The mechanisms by which these effects of cholesterol are reversed by tegaserod are unknown, but relate to removal of an inhibitory effect of cholesterol on enteric nerves.
PMCID: PMC1434748  PMID: 16504074
10.  Changes of smooth muscle contractile filaments in small bowel atresia 
AIM: To investigate morphological changes of intestinal smooth muscle contractile fibres in small bowel atresia patients.
METHODS: Resected small bowel specimens from small bowel atresia patients (n = 12) were divided into three sections (proximal, atretic and distal). Standard histology hematoxylin-eosin staining and enzyme immunohistochemistry was performed to visualize smooth muscle contractile markers α-smooth muscle actin (SMA) and desmin using conventional paraffin sections of the proximal and distal bowel. Small bowel from age-matched patients (n = 2) undergoing Meckel’s diverticulum resection served as controls.
RESULTS: The smooth muscle coat in the proximal bowel of small bowel atresia patients was thickened compared with control tissue, but the distal bowel was unchanged. Expression of smooth muscle contractile fibres SMA and desmin within the proximal bowel was slightly reduced compared with the distal bowel and control tissue. There were no major differences in the architecture of the smooth muscle within the proximal bowel and the distal bowel. The proximal and distal bowel in small bowel atresia patients revealed only minimal differences regarding smooth muscle morphology and the presence of smooth muscle contractile filament markers.
CONCLUSION: Changes in smooth muscle contractile filaments do not appear to play a major role in postoperative motility disorders in small bowel atresia.
PMCID: PMC3386323  PMID: 22791945
Small bowel atresia; Enteric nervous system; Smooth muscle; Motility disorder
11.  A nitric oxide-like factor mediates nonadrenergic-noncholinergic neurogenic relaxation of penile corpus cavernosum smooth muscle. 
Journal of Clinical Investigation  1991;88(1):112-118.
This study was initiated to characterize nonadrenergic-noncholinergic (NANC) inhibitory neurotransmission in penile corpus cavernosum. Using organ baths, isometric tension measurements were made in strips of human and rabbit corpus cavernosum. In examining endothelium-mediated responses, cumulative additions of exogenous acetylcholine elicited dose-dependent relaxations which were significantly reduced or completely inhibited in tissues treated with NG-monomethyl L-arginine (L-NMMA; an inhibitor of nitric oxide synthesis), oxyhemoglobin (a nitric oxide scavenger), or methylene blue (a guanylate cyclase blocker). Tissues exposed to hypoxic conditions (PO2 = 5-10 mmHg) also did not respond to exogenous acetylcholine. Mechanical removal of the endothelium in human corporal strips or in situ treatment of rabbit corpora with detergent blocked the relaxation to acetylcholine. Transmural electrical stimulation of corporal tissue strips denuded of functional endothelium, in the presence of adrenergic blockade with bretylium and muscarinic receptor blockade with atropine, caused frequency-dependent relaxation. This neurogenic relaxation was reduced or prevented by L-NMMA, oxyhemoglobin, methylene blue, and hypoxia. The effects of L-NMMA were reversed by L-arginine and the effects of hypoxia were readily reversed by normoxic conditions. Authentic, exogenous nitric oxide relaxed corporal strips which were contracted with adrenergic agonists and this effect was significantly inhibited by oxyhemoglobin. It is concluded that (a) endothelium-mediated responses of corpus cavernosum smooth muscle are mediated by a diffusible nitric oxide-like substance; (b) NANC neurogenic inhibitory responses do not require functional endothelium, and (c) nitric oxide, or a closely related substance, may act as an inhibitory neurotransmitter in penile corpus cavernosum smooth muscle.
PMCID: PMC296010  PMID: 1647413
12.  Plasticity of non-adrenergic non-cholinergic bladder contractions in rats after chronic spinal cord injury 
Brain research bulletin  2011;86(1-2):91-96.
The purpose of this study was to examine the pharmacologic plasticity of cholinergic, non-adrenergic non-cholinergic (NANC), and purinergic contractions in neurogenic bladder strips from spinal cord injured (SCI) rats. Bladder strips were harvested from female rats three to four weeks after T9–T10 spinal cord transection. The strips were electrically stimulated using two experimental protocols to compare the contribution of muscarinic and NANC/purinergic contractions in the presence and the absence of carbachol or muscarine. The endpoints of the study were: (1) percent NANC contraction that was unmasked by the muscarinic antagonist 4-DAMP, and (2) P2X purinergic contraction that was evoked by α,β–methylene ATP. NANC contraction accounted for 78.5% of the neurally evoked contraction in SCI bladders. When SCI bladder strips were treated with carbachol (10 µM) prior to 4-DAMP (500 nM), the percent NANC contraction decreased dramatically to only 13.1% of the neurally evoked contraction (p=0.041). This was accompanied by a substantial decrease in α,β–methylene ATP evoked P2X contraction, and desensitization of purinergic receptors (the ratio of subsequent over initial P2X contraction decreased from 97.2% to 42.1%, p=0.0017). Sequential activation of the cholinergic receptors with carbachol (or with muscarine in neurally intact bladders) and unmasking of the NANC response with 4-DAMP switched the neurally evoked bladder contraction from predominantly NANC to predominantly cholinergic. We conclude that activation of muscarinic receptors (with carbachol or muscarine) blocks NANC and purinergic contractions in neurally intact or in SCI rat bladders. The carbachol-induced inhibition of the NANC contraction is expressed more in SCI bladders compared to neurally intact bladders. Along with receptor plasticity, this change in bladder function may involve P2X-independent mechanisms.
PMCID: PMC3156315  PMID: 21689735
neurogenic bladder; bladder contractility; spinal cord injury; purinergic receptor; cholinergic receptor
13.  Commonly used intravenous anesthetics decrease bladder contractility: An in vitro study of the effects of propofol, ketamine, and midazolam on the rat bladder 
This study was designed to test the hypothesis that propofol, ketamine, and midazolam could alter the contractile activity of detrusor smooth muscle.
Materials and Methods:
Four detrusor muscle strips isolated from each rat bladder (n = 12) were placed in 4 tissue baths containing Krebs-Henseleit solution. The carbachol (10 −8to 10−4mol/L)-induced contractile responses as well as 5, 10, 20, 30, 40, 50 Hz electrical field stimulation (EFS)-evoked contractile responses of the detrusor muscles were recorded using isometric contraction measurements. After obtaining basal responses, the in vitro effects of propofol, ketamine, midazolam (10−5 to 10−3 mol/L), and saline on the contractile responses of the detrusor muscle strips were recorded and evaluated.
All the 3 drugs reduced the carbachol-induced and/or EFS-evoked contractile responses of rat detrusor smooth muscles in different degrees. Midazolam (10−4 to 10−3 mol/L) caused a significant decrease in the contractile responses elicited by either EFS or carbachol (P=0.000−0.013). Propofol (10−3mol/L) caused a decrease only in EFS-evoked contractile responses (P=0.001−0.004) and ketamine (10−3mol/L) caused a decrease only in carbachol-induced contractile responses (P=0.001−0.034).
We evaluated the effects of the 3 different intravenous anesthetics on detrusor contractile responses in vitro and found that there are possible interactions between anesthetic agents and detrusor contractile activity. The depressant effects of midazolam on the contractile activity were found to be more significant than ketamine and propofol. Despite the necessity of further studies, it could be a piece of wise advice to clinicians to keep the probable alterations due to intravenous anesthetics in mind, while evaluating the results of urodynamic studies in children under sedation.
PMCID: PMC2978435  PMID: 21116355
Bladder; smooth muscle contractility; propofol; ketamine; midazolam
14.  Alterations of Colonic Contractility in an Interleukin-10 Knockout Mouse Model of Inflammatory Bowel Disease 
Inflammatory bowel disease is commonly accompanied by colonic dysmotility and causes changes in intestinal smooth muscle contractility. In this study, colonic smooth muscle contractility in a chronic inflammatory condition was investigated using smooth muscle tissues prepared from interleukin-10 knockout (IL-10−/−) mice.
Prepared smooth muscle sections were placed in an organ bath system. Cholinergic and nitrergic neuronal responses were observed using carbachol and electrical field stimulation with L-NG-nitroarginine methyl ester (L-NAME). The expression of interstitial cells of Cajal (ICC) networks, muscarinic receptors, neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) was observed via immunofluorescent staining.
The spontaneous contractility and expression of ICC networks in the proximal and distal colon was significantly decreased in IL-10−/− mice compared to IL-10+/+ mice. The contractility in response to carbachol was significantly decreased in the proximal colon of IL-10−/− mice compared to IL-10+/+ mice, but no significant difference was found in the distal colon. In addition, the expression of muscarinic receptor type 2 was reduced in the proximal colon of IL-10−/− mice. The nictric oxide-mediated relaxation after electrical field stimulation was significantly decreased in the proximal and distal colon of IL-10−/− mice. In inflamed colon, the expression of nNOS decreased, whereas the expression of iNOS increased.
These results suggest that damage to the ICC network and NOS system in the proximal and distal colon, as well as damage to the smooth muscle cholinergic receptor in the proximal colon may play an important role in the dysmotility of the inflamed colon.
PMCID: PMC4288096  PMID: 25537671
Colon; Contractility; Inflammatory bowel diseases; Interleukin-10
To determine mechanisms of action of the gasotransmitter hydrogen sulfide (H2S) on contractile activity in longitudinal muscle of rat ileum.
Ileal longitudinal muscle strips were prepared to measure isometric contractions. Effects of sodium hydrosulfide (NaHS), a donor of H2S, were evaluated on spontaneous contractile activity and after enhanced contractile activity with bethanechol. L-cysteine was evaluated as a potential endogenous donor of H2S. We evaluated involvement of extrinsic nerves, enteric nervous system, visceral afferent nerves, nitric oxide, and K+ATP channel and K+Ca channel activity on the action of H2S using non-adrenergic/non-cholinergic conditions, tetrodotoxin, capsaicin, L-NG-nitro arginine (L-NNA), glibenclamide, and apamin, respectively, as well as electrical field stimulation.
NaHS dose-dependently and reversibly inhibited spontaneous and bethanechol-stimulated contractile activity (p<0.05). L-cysteine had no inhibitory effect. Non-adrenergic/non-cholinergic conditions, tetrodotoxin, capsaicin, L-NNA, glibenclamide, or apamin had no major effect on total contractile activity by NaHS, although both tetrodotoxin and apamin decreased the frequency of bethanechol-enhanced contractile activity (p<0.05). We could not demonstrate H2S release by electrical field stimulation but did show that inhibition of cystathionine β synthase, an endogenous source of H2S, augmented the inhibitory effect of low-frequency electrical field stimulation.
H2S inhibits contractile activity of ileal longitudinal muscle dose-dependently but not through pathways mediated by the extrinsic or enteric nervous system, visceral afferent nerves, nitric oxide, K+ATP channels, or K+Ca channels.
PMCID: PMC3046388  PMID: 21082276
intestinal motility; gasotransmitter; hydrogen sulfide; longitudinal muscle; physiology; motility; contractile activity; ileum longitudinal smooth muscle
16.  Gastric Electrical Stimulation 
Executive Summary
The objective of this analysis was to assess the effectiveness, safety and cost-effectiveness of gastric electrical stimulation (GES) for the treatment of chronic, symptomatic refractory gastroparesis and morbid obesity.
Gastroparesis - Epidemiology
Gastroparesis (GP) broadly refers to impaired gastric emptying in the absence of obstruction. Clinically, this can range from the incidental detection of delayed gastric emptying in an asymptomatic person to patients with severe nausea, vomiting and malnutrition. Symptoms of GP are nonspecific and may mimic structural disorders such as ulcer disease, partial gastric or small bowel obstruction, gastric cancer, and pancreaticobiliary disorders.
Gastroparesis may occur in association with diabetes, gastric surgery (consequence of peptic ulcer surgery and vagotomy) or for unknown reasons (idiopathic gastroparesis). Symptoms include early satiety, nausea, vomiting, abdominal pain and weight loss. The majority of patients with GP are women.
The relationship between upper gastrointestinal symptoms and the rate of gastric emptying is considered to be weak. Some patients with markedly delayed gastric emptying are asymptomatic and sometimes, severe symptoms may remit spontaneously.
Idiopathic GP may represent the most common form of GP. In one tertiary referral retrospective series, the etiologies in 146 GP patients were 36% idiopathic, 29% diabetic, 13% postgastric surgery, 7.5% Parkinson’s disease, 4.8% collagen vascular disorders, 4.1% intestinal pseudoobstruction and 6% miscellaneous causes.
The true prevalence of digestive symptoms in patients with diabetes and the relationship of these symptoms to delayed gastric emptying are unknown. Delayed gastric emptying is present in 27% to 58% of patients with type 1 diabetes and 30% with type 2 diabetes. However, highly variable rates of gastric emptying have been reported in type 1 and 2 diabetes, suggesting that development of GP in patients with diabetes is neither universal nor inevitable. In a review of studies examining gastric emptying in patients with diabetes compared to control patients, investigators noted that in many cases the magnitude of the delay in gastric emptying is modest.
GP may occur as a complication of a number of different surgical procedures. For example, vagal nerve injury may occur in 4% to 40% of patients who undergo laparoscopic fundoplication1 for gastroesophageal reflux disease.
The prevalence of severe, refractory GP is scantily reported in the literature. Using data from a past study, it has been estimated that the prevalence of severe, symptomatic and refractory GP in the United States population is 0.017%. Assuming an Ontario population of 13 million, this would correspond to approximately 2,000 people in Ontario having severe, symptomatic, refractory GP.
The incidence of severe refractory GP estimated by the United States Food and Drug Administration (FDA) is approximately 4,000 per year in the United States. This corresponds to about 150 patients in Ontario. Using expert opinion and FDA data, the incidence of severe refractory GP in Ontario is estimated to be about 20 to 150 per year.
Treatment for Gastroparesis
To date, there have been no long-term studies confirming the beneficial effects of maintaining euglycemia on GP symptoms. However, it has been suggested that consistent findings of physiologic studies in healthy volunteers and diabetes patients provides an argument to strive for near-normal blood glucose levels in affected diabetes patients.
Dietary measures (e.g., low fibre, low fat food), prokinetic drugs (e.g., domperidone, metoclopramide and erythromycin) and antiemetic or antinausea drugs (e.g, phenothiazines, diphenhydramine) are generally effective for symptomatic relief in the majority of patients with GP.
For patients with chronic, symptomatic GP who are refractory to drug treatment, surgical options may include jejunostomy tube for feeding, gastrotomy tube for stomach decompression and pyloroplasty for gastric emptying.
Few small studies examined the use of botulinum toxin injections into the pyloric sphincter. However, the contribution of excessive pyloric contraction to GP has been insufficiently defined and there have been no controlled studies of this therapy.
Treatment with GES is reversible and may be a less invasive option compared to stomach surgery for the treatment of patients with chronic, drug-refractory nausea and vomiting secondary to GP. In theory, GES represents an intermediate step between treatment directed at the underlying pathophysiology, and the treatment of symptoms. It is based on studies of gastric electrical patterns in GP that have identified the presence of a variety of gastric arrhythmias. Similar to a cardiac pacemaker, it was hypothesized that GES could override the abnormal rhythms, stimulate gastric emptying and eliminate symptoms.
Morbid Obesity Epidemiology
Obesity is defined as a body mass index (BMI) of at last 30 kg/m2. Morbid obesity is defined as a BMI of at least 40 kg/m2 or at least 35 kg/m2 with comorbid conditions. Comorbid conditions associated with obesity include diabetes, hypertension, dyslipidemias, obstructive sleep apnea, weight-related arthropathies, and stress urinary incontinence.
In the United States, the age-adjusted prevalence of extreme obesity (BMI ≥ 40 kg/m2) for adults aged 20 years and older has increased significantly in the population, from 2.9% (1988–1994) to 4.7% (1999–2000). An expert estimated that about 160,000 to 180,000 people are morbidly obese in Ontario.
Treatment for Morbid Obesity
Diet, exercise, and behavioural therapy are used to help people lose weight.
Bariatric surgery for morbid obesity is considered an intervention of last resort for patients who have attempted first-line forms of medical management.
Gastric stimulation has been investigated for the treatment of morbid obesity; the intention being to reduce appetite and induce early satiety possibly due to inhibitory effects on gastric motility and effects on the central nervous system (CNS) and hormones related to satiety and/or appetite.
Possible advantages to GES for the treatment of morbid obesity include reversibility of the procedure, less invasiveness than some bariatric procedures, e.g., gastric bypass, and less side effects (e.g., dumping syndrome).
The Device
Electrical stimulation is delivered via an implanted system that consists of a neurostimulator and 2 leads. The surgical procedure can be performed via either an open or laparoscopic approach. An external programmer used by the physician can deliver instructions to the GES, i.e., adjust the rate and amplitude of stimulation (Figure 1). GES may be turned off by the physician at any time or may be removed. The battery life is approximately 4-5 years
For treatment of GP, the GES leads are secured in the muscle of the lower stomach, 10 cm proximal to the pylorus (the opening from the stomach to the intestine), 1 cm apart and connected to an implantable battery-powered neurostimulator which is placed in a small pocket in the abdominal wall
For treatment of morbid obesity, GES leads are implanted along the lesser curvature of the stomach where the vagal nerve branches spread, approximately 8 cm proximal to the pylorus. However, the implant positioning of the leads has been variably reported in the literature.
Regulatory Status
The Enterra Therapy System and the Transcend II Implantable Gastric Stimulation System (Medtronic Inc.) are both licensed as class 3 devices by Health Canada (license numbers 60264 and 66948 respectively). The Health Canada indications for use are:
Enterra Therapy System
“For use in the treatment of chronic intractable (drug-refractory) nausea and vomiting.”
Transcend II Implantable Gastric Stimulation System
“For use in weight reduction for obese adults with a body mass index greater than 35.”
The GES device that is licensed by Health Canada for treatment of GP, produces high-frequency GES. Most clinical studies examining GES for GP have used high-frequency (4 times the intrinsic slow wave frequency, i.e., 12 cycles per minute), low energy, short duration pulses. This type of stimulation does not alter gastric muscular contraction and has no effect on slow wave dysrhythmias. The mechanism of action is unclear but it is hypothesized that high-frequency GES may act on sensory fibers directed to the CNS.
The GES device licensed by Health Canada for treatment of morbid obesity produces low-frequency GES, which is close to or just above the normal/native gastric slow wave cycle (approximately 3 cycles/min.). This pacing uses low-frequency, high-energy, long-duration pulses to induce propagated slow waves that replace the spontaneous ones. Low-frequency pacing does not invoke muscular contractions.
Most studies examining the use of GES for the treatment of morbid obesity use low-frequency GES. Under normal circumstances, the gastric slow wave propagates distally and determines the frequency and propagation direction of gastric peristalsis. Low-frequency GES aims to produce abnormal gastric slow waves that can induce gastric dysrhythmia, disrupt regular propagation of slow waves, cause hypomotility of the stomach, delay gastric emptying, reduce food intake, prolong satiety, and produce weight loss.
In the United States, the Enterra Therapy System is a Humanitarian Use Device (HUD), meaning it is a medical device designated by the FDA for use in the treatment of medical conditions that affect fewer than 4,000 individuals per year.2 The Enterra Therapy System is indicated for “the treatment of chronic, drug- refractory nausea and vomiting secondary to GP of diabetes or idiopathic etiology” (not postsurgical etiologies).
GES for morbid obesity has not been approved by the FDA and is for investigational use only in the United States.
Review Strategy
The Medical Advisory Secretariat systematically reviewed the literature to assess the effectiveness, safety, and cost-effectiveness of GES to treat patients who have: a) chronic refractory symptomatic GP; or b) morbid obesity.
The Medical Advisory Secretariat used its standard search strategy to retrieve international health technology assessments and English-language journal articles from selected databases.
The GRADE approach was used to systematically and explicitly make judgments about the quality of evidence and strength of recommendations.
As stated by the GRADE Working Group, the following definitions were used in grading the quality of the evidence in Tables 1 and 2.
GRADE Quality of Studies – Gastroparesis
Confounders related to diabetes.
Possible Type 2 error for subgroup analyses.
Subjective self-reported end point.
Posthoc change in primary end point analysis.
No sample size justification.
Concomitant prokinetic/antiemetic therapy.
Only 1 RCT (with different results for FDA and publication).
GES originally hypothesized to correct gastric rhythms, stimulate gastric emptying and therefore eliminate symptoms.
Now hypothesized to directly act on neurons to the CNS to control symptoms.
Weak correlation between symptoms and gastric emptying.
Unclear whether gastric emptying is still considered an end point to investigate.
GRADE Quality of Studies – Morbid Obesity
No sample size calculation.
Small sample size.
No ITT analysis.
Lack of detail regarding dropouts.
Possible Type 2 error.
Sparse details about randomization/blinding.
Full, final results not published.
Only 1 RCT (technically grey literature).
Economic Analysis
No formal economic analysis was identified in the literature search.
The Alberta Heritage Foundation for Medical Research reported that the cost of implanting a GES in the United States for the treatment of GP is estimated to be $30,000 US. In Canada, the device costs approximately $10,700 Cdn; this does not include costs associated with the physician’s training, the implantation procedure, or device programming and maintenance.
Ontario Context
There is no Schedule of Benefits code for GES.
There is no Canadian Classification of Health Interventions Index (CCI) procedure code for GES.
Since the ICD-10 diagnosis code for gastroparesis falls under K31.8 “Other specified diseases of the stomach and duodenum”, it is impossible to determine how many patients in Ontario had discharge abstracts because of gastroparesis.
In 2005, there were less than 5 out-of-country requests for GES (for either consultation only or for surgery).
The prevalence of severe, refractory GP is variably reported in the literature.
The Alberta Heritage Foundation for Medical Research estimated that the prevalence of severe, symptomatic and medically refractory GP in the United States population was 0.017%. Assuming a total Ontario population of 13 million, this would correspond to a budget impact of approximately $23.6 M
Cdn ($10,700 Cdn x 2,210 patients) for the device cost alone.
The incidence of severe refractory GP estimated by the FDA is approximately 4,000 per year in the United States. This corresponds to about 150 patients in Ontario. Using expert opinion and FDA data, the incidence of severe refractory GP in Ontario is estimated to be about 20 to 150 per year. This corresponds to a budget impact of approximately $107,000 Cdn to $1.6M Cdn per year for the device cost alone.
Morbid Obesity
An expert in the field estimated that there are 160,000 to 180,000 people in Ontario who are morbidly obese. This would correspond to a budget impact of approximately $1.7B Cdn to $1.9B Cdn for the device cost alone (assuming 100% uptake). However, the true uptake of GES for morbid obesity is unknown in relation to other types of bariatric surgery (which are more effective).
As per the GRADE Working Group, overall recommendations consider 4 main factors.
The tradeoffs, taking into account the estimated size of the effect for the main outcome, the confidence limits around those estimates and the relative value placed on the outcome.
The quality of the evidence.
Translation of the evidence into practice in a specific setting, taking into consideration important factors that could be expected to modify the size of the expected effects such as proximity to a hospital or availability of necessary expertise.
Uncertainty about the baseline risk for the population of interest.
The GRADE Working Group also recommends that incremental costs of healthcare alternatives should be considered explicitly alongside the expected health benefits and harms. Recommendations rely on judgments about the value of the incremental health benefits in relation to the incremental costs. The last column in Table 3 shows the overall trade-off between benefits and harms and incorporates any risk/uncertainty.
For GP, the overall GRADE and strength of the recommendation is “weak” – the quality of the evidence is “low” (uncertainties due to methodological limitations in the study design in terms of study quality, consistency and directness), and the corresponding risk/uncertainty is increased due to a budget impact of approximately $107,000 Cdn to $1.6M Cdn for the device cost alone, while the cost-effectiveness of GES is unknown and difficult to estimate considering that there are no high-quality studies of effectiveness. Further evidence of effectiveness should be available in the future since there is a RCT underway that is examining the use of GES in patients with severe refractory GP associated with diabetes and idiopathic etiologies ( identifier NCT00157755).
For morbid obesity, the overall GRADE and strength of the recommendation is “weak” – the quality of the evidence is “low” (uncertainties due to methodological limitations in the study design in terms of study quality and consistency), and the corresponding risk/uncertainty is increased due to a budget impact of approximately $1.7B Cdn to $1.9B Cdn for the device cost alone (assuming 100% uptake) while the cost-effectiveness of GES is unknown and difficult to estimate considering that there are no high quality studies of effectiveness. However, the true uptake of GES for morbid obesity is unknown in relation to other types of bariatric surgery (which are more effective).
Overall GRADE and Strength of Recommendation (Including Uncertainty)
PMCID: PMC3413096  PMID: 23074486
17.  Effect of Fructus Psoraleae on motility of gallbladder isolated smooth muscle strips from guinea pigs 
AIM: To observe the effect of Fructus Psoraleae on motility of isolated gallbladder muscle strips of guinea pigs and its mechanism.
METHODS: Guinea pigs were hit to lose consciousness and the whole gallbladder was removed quickly. Two or three smooth muscle strips (8 mm × 3 mm) were cut along a longitudinal direction. The mucosa was gently removed. Every longitudinal muscle strip was suspended in a tissue chamber which was continuously perfused with 5 mL Krebs solution (37°C), pH 7.4, and aerated with 950 mL/L O2 and 50 mL /L CO2. The isometric response was recorded with an ink-writing recorder. After 2 h equilibration under 1 g-load, 50 μL Fructus Psoraleae (10, 20, 70, 200, 700, 1000 g/L) was added cumulatively into the tissue chamber in turn every 2 min to observe their effects on gallbladder muscle strips (cumulating final concentration of Fructus Psoraleae was 0.1, 0.3, 1.0, 3.0, 10.0, 20.0 g/L). The antagonists, including 4-DAMP, benzhydramine, hexamethonium, phentolamine, verapamil and idomethine were given 2 min before Fructus Psoraleae respectively to investigate the mechanisms involved.
RESULTS: Fructus Psoraleae dose-dependently increased the resting tension (r = 0.992, P < 0.001), decreased the mean contractile amplitude (r = 0.970, P < 0.001) and meanwhile increased the contractile frequency of the gallbladder muscle strip in vitro (r = 0.965, P < 0.001). The exciting action of Fructus Psoraleae on the resting tension could be partially blocked by 4-DAMP (the resting tension decreased from 1.37 ± 0.41 to 0.70 ± 0.35, P < 0.001), benzhydramine (from 1.37 ± 0.41 to 0.45 ± 0.38, P < 0.001), hexamethonium (from 1.37 ± 0.41 to 0.94 ± 0.23, P < 0.05), phentolamine ( from 1.37 ± 0.41 to 0.89 ± 0.22, P < 0.01) and verapamil (from 1.37 ± 0.41 to 0.94 ± 0.26, P < 0.05). But the above antagonists had no significant effect on the action of Fructus Psoraleae–induced mean contractile amplitude (P > 0.05). Moreover, the increase of the contractile frequency due to Fructus Psoraleae was inhibited by 4-DAMP (decreased from 8.3 ± 1.2 to 6.8 ± 0.5, P < 0.01) and hexamethonium (from 8.3 ± 1.2 to 7.0 ± 0.9, P < 0.05). Idomethine had no significant effect on the Fructus Psoraleae-induced responses (P > 0.05).
CONCLUSION: Fructus Psoraleae enhances the motility of isolated gallbladder muscle strips from guinea pigs, in a dose-dependent manner. The effect of Fructus Psoraleae is partly related to M3, N receptor, α receptor, H1 receptor, Ca2+ channel, but not related to prostaglandin.
PMCID: PMC4088023  PMID: 16937536
Fructus Psoraleae; Gallbladder smooth muscle strips; M3, N, α, H1 receptors; Ca2+ channel; Prostaglandin
Peptides  2007;28(9):1688-1699.
In 1970, Drs. Said and Mutt isolated a novel peptide from porcine intestinal extracts with powerful vasoactive properties, and named it vasoactive intestinal peptide (VIP). Since then, the biological actions of VIP in the gut as well as its signal transduction pathways have been extensively studied. A variety of in vitro and in vivo studies have indicated that VIP, expressed in intrinsic non-adrenergic non-cholinergic (NANC) neurons, is a potent regulator of gastrointestinal (GI) motility, water absorption and ion flux, mucus secretion and immune homeostasis. These VIP actions are believed to be mediated mainly by interactions with highly expressed VPAC1 receptors and the production of nitric oxide (NO). Furthermore, VIP has been implicated in numerous physiopathological conditions affecting the human gut, including pancreatic endocrine tumors secreting VIP (VIPomas), insulin-dependent diabetes, Hirschsprung’s disease, and inflammatory bowel syndromes such as Crohn’s disease and ulcerative colitis. To further understand the physiological roles of VIP on the GI tract, we have begun to analyze the anatomical and physiological phenotype of C57BL/6 mice lacking the VIP gene. Herein, we demonstrate that the overall intestinal morphology and light microscopic structure is significantly altered in VIP−/− mice. Macroscopically there is an overall increase in weight, and decrease in length of the bowel compared to wild type (WT) controls. Microscopically, the phenotype was characterized by thickening of smooth muscle layers, increased villi length, and higher abundance of goblet cells. Alcian blue staining indicated that the latter cells were deficient in mucus secretion in VIP−/− mice. The differences became more pronounced from the duodenum to the distal jejunum or ileum of the small bowel but, became much less apparent or absent in the colon with the exception of mucus secretion defects. Further examination of the small intestine revealed larger axonal trunks and unusual unstained patches in myenteric plexus. Physiologically, the VIP−/− mice showed an impairment in intestinal transit. Moreover, unlike WT C57BL/6 mice, a significant percentage of VIP−/− mice died in the first postnatal year with overt stenosis of the gut.
PMCID: PMC2042583  PMID: 17606312
19.  Ca2+-Dependent Contraction by the Saponoside Escin in Rat Vena Cava. Implications in Venotonic Treatment of Varicose Veins 
Saponosides (horse chestnut seed extract, escin) and flavonoids (diosmin, Daflon 500) exhibit venotonic properties that have been utilized in treatment of varicose veins. However, the cellular mechanisms underlying the venotonic properties of escin and diosmin are unclear. Because Ca2+ is a major regulator of venous smooth muscle (VSM) function, we tested the hypothesis that escin and diosmin promote Ca2+-dependent venous contraction.
Rings of inferior vena cava (IVC) from male rats were suspended in a tissue bath for measurement of isometric contraction. Following control contraction to 96 mM KCl, the effects of escin and diosmin (10−10 to 10−4 M) on vein contraction were measured. To test the role of intracellular Ca2+ release, the vein response to escin and diosmin was measured in Ca2+-free (2mM EGTA) Krebs. To test for Ca2+-dependent effects, IVC segments were pretreated with escin or diosmin (10−4 M) in 0 Ca2+ Krebs, then extracellular CaCl2 (0.1, 0.3, 0.6, 1, 2.5 mM) was added and the [Ca2+]e-contraction relationship was constructed. To test for synergistic effects of diosmin, IVC segments were pretreated with diosmin (10−4 M) then stimulated with KCl (16 to 96 mM) or escin (10−10 to 10−4 M) and vein contraction was measured. Contraction data were presented as mg/mg tissue (means±SEM).
In IVC segments incubated in normal Krebs (2.5 mM Ca2+), escin caused concentration-dependent contraction (max 104.3±19.6 at 10−4 M). Escin-induced contraction was not a rigor state, because after washing with Krebs the veins returned to a relaxed state. In Ca2+-free Krebs, there was essentially no contraction to escin. In escin-treated veins incubated in 0 Ca2+ Krebs, stepwise addition of extracellular CaCl2 caused corresponding increases in contraction (max 80.0±11.1 at 2.5 mM). In the absence of escin, the α-adrenergic agonist phenylephrine (PHE, 10−5 M), angiotensin II (AngII, 10−6 M), and membrane depolarization by KCl (96 mM) caused significant contraction (122.5±45.1, 114.2±12.2 and 221.7±35.4, respectively). In IVC segments pretreated with escin (10−4 M), the contractile response to PHE (9.7±2.6), AngII (36.0±9.1) and KCl (82.3±10.2) was significantly reduced. Diosmin (10−4 M) caused small contraction in normal Krebs (11.7±1.9) and Ca2+-free Krebs (4.2±2.2). In diosmin-treated veins incubated in 0 Ca2+ Krebs, addition of extracellular CaCl2 caused minimal contraction. Diosmin did not enhance the IVC contraction to PHE, AngII, or escin, but enhanced the contractile response to KCl (24 to 51 mM).
In rat IVC, escin induces extracellular Ca2+-dependent contraction, but disrupts α-adrenergic and AT1R receptor-mediated pathways, and depolarization-induced contraction. The initial venotonic benefits of escin may be offset by disruption of vein response to endogenous venoconstrictors, limiting its long-term therapeutic benefits in varicose veins. Diosmin does not cause venous contraction or potentiate the venotonic effects of endogenous venoconstrictors or escin ex vivo, and its use as venotonic may need to be further evaluated.
PMCID: PMC3140579  PMID: 21498026
escin; diosmin; varicose veins; vascular smooth muscle; calcium
20.  Effects of sodium metabisulphite on guinea pig contractile airway smooth muscle responses in vitro. 
Thorax  1995;50(8):875-879.
BACKGROUND--Sodium metabisulphite (MBS) is known to induce bronchoconstriction in asthmatic patients. The effects of MBS on guinea pig airway smooth muscle and on neurally mediated contraction in vitro have been examined. METHODS--Tracheal and bronchial airway segments were placed in oxygenated buffer solution and electrical field stimulation was performed in the presence of indomethacin (10(-5) M) and propranolol (10(-6) M) for the measurement of isometric tension. Atropine (10(-6) M) was added to bronchial tissues. RESULTS--Concentrations of MBS up to 10(-3) M had no direct effect on airway smooth muscle contraction and did not alter either tracheal smooth muscle contraction induced by electrical field stimulation at all frequencies or acetylcholine-induced tracheal smooth muscle contraction. There was a similar response in the absence of epithelium, except for potentiation of the response induced by electrical field stimulation at 0.5 Hz (24 (10)% increase). However, MBS (10(-5), 10(-6) and 10(-7) M) augmented neurally-mediated non-adrenergic non-cholinergic contractile responses in the bronchi (13.3 (3.2)%, 23.8 (9.6)%, and 6.4 (1.6)%, respectively). MBS had no effect on the contractile response induced by substance P, but at higher concentrations (10(-3) M and 10(-4) M) it caused a time-dependent attenuation of responses induced by either electrical field stimulation or exogenously applied acetylcholine or substance P. CONCLUSIONS--MBS had no direct contractile responses but enhanced bronchoconstriction induced by activation of non-cholinergic neural pathways in the bronchus, probably through increased release of neuropeptides. At high concentrations MBS inhibited contractile responses initiated by receptor or neural stimulation.
PMCID: PMC474910  PMID: 7570440
21.  Global Transcript Profiles of Fat in Monozygotic Twins Discordant for BMI: Pathways behind Acquired Obesity  
PLoS Medicine  2008;5(3):e51.
The acquired component of complex traits is difficult to dissect in humans. Obesity represents such a trait, in which the metabolic and molecular consequences emerge from complex interactions of genes and environment. With the substantial morbidity associated with obesity, a deeper understanding of the concurrent metabolic changes is of considerable importance. The goal of this study was to investigate this important acquired component and expose obesity-induced changes in biological pathways in an identical genetic background.
Methods and Findings
We used a special study design of “clonal controls,” rare monozygotic twins discordant for obesity identified through a national registry of 2,453 young, healthy twin pairs. A total of 14 pairs were studied (eight male, six female; white), with a mean ± standard deviation (SD) age 25.8 ± 1.4 y and a body mass index (BMI) difference 5.2 ± 1.8 kg/m2. Sequence analyses of mitochondrial DNA (mtDNA) in subcutaneous fat and peripheral leukocytes revealed no aberrant heteroplasmy between the co-twins. However, mtDNA copy number was reduced by 47% in the obese co-twin's fat. In addition, novel pathway analyses of the adipose tissue transcription profiles exposed significant down-regulation of mitochondrial branched-chain amino acid (BCAA) catabolism (p < 0.0001). In line with this finding, serum levels of insulin secretion-enhancing BCAAs were increased in obese male co-twins (9% increase, p = 0.025). Lending clinical relevance to the findings, in both sexes the observed aberrations in mitochondrial amino acid metabolism pathways in fat correlated closely with liver fat accumulation, insulin resistance, and hyperinsulinemia, early aberrations of acquired obesity in these healthy young adults.
Our findings emphasize a substantial role of mitochondrial energy- and amino acid metabolism in obesity and development of insulin resistance.
Leena Peltonen and colleagues uncover the metabolic changes that result from obesity through an analysis of genetically identical twin pairs in which one was obese and the other was not.
Editors' Summary
Around the world, the proportion of people who are obese (people with an unhealthy amount of body fat) is increasing. In the US, for example, 1 adult in 7 was obese in the mid 1970s. That is, their body mass index (BMI)—their weight in kilograms divided by their height in meters squared—was more than 30. Nowadays, 1 US adult in 3 has a BMI this high and, by 2025, it is predicted that 1 in 2 will be obese. This obesity epidemic is being driven by lifestyle changes that encourage the over-consumption of energy-rich foods and discourage regular physical activity. The resultant energy imbalance leads to weight gain (the excess energy is stored as body fat or adipose tissue) and also triggers numerous metabolic changes, alterations in the chemical processes that convert food into the energy and various substances needed to support life. These obesity-related metabolic changes increase a person's risk of developing adverse health conditions such as diabetes, a condition in which dangerously high levels of sugar from food accumulate in the blood.
Why Was This Study Done?
The changes in human fat in obesity have not been completely understood, although the abnormal metabolism of adipose tissue is increasingly seen as playing a critical part in excessive weight gain. It has been very difficult to decipher which molecular and metabolic changes associated with obesity are the result of becoming obese, and which might contribute towards the acquisition of obesity in humans in the first place. To discover more about the influence of environment on obesity-induced metabolic changes, the researchers in this study have investigated these changes in pairs of genetically identical twins.
What Did the Researchers Do and Find?
The researchers recruited 14 pairs of genetically identical Finnish twins born between 1975 and 1979 who were “obesity discordant”—that is, one twin of each pair had a BMI of about 25 (not obese); the other had a BMI of about 30 (obese). The researchers took fat and blood samples from each twin, determined the insulin sensitivity of each, and measured the body composition and various fat stores of each. They found that the obese twins had more subcutaneous, intra-abdominal, and liver fat and were less insulin sensitive than the non-obese twins. Insulin sensitivity correlated with the amount of liver fat. Analysis of gene expression in the fat samples showed that 19 gene pathways (mainly inflammatory pathways) were expressed more strongly (up-regulated) in the obese twins than the non-obese twins, whereas seven pathways were down-regulated. The most highly down-regulated pathway was a mitochondrial pathway involved in amino acid breakdown, but mitochondrial energy metabolism pathways were also down-regulated. Finally, mitochondrial DNA copy number in fat was reduced in the obese twins by nearly half, a novel observation that could partly account for the obesity-induced metabolic defects of these individuals.
What Do These Findings Mean?
These and other findings identify several pathways that are involved in the development of obesity and insulin resistance. In particular, they suggest that changes in mitochondrial energy production pathways and in mitochondrial amino acid metabolism pathways could play important roles in the development of obesity and of insulin resistance and in the accumulation of liver fat even in young obese people. The study design involving identical twins has here produced some evidence for aberrations in molecules critical for acquired obesity. The results suggest that careful management of obesity by lifestyle changes has the potential to correct the obesity-related metabolic changes in fat that would otherwise lead to diabetes and other adverse health conditions in obese individuals. In addition, they suggest that the development of therapies designed to correct mitochondrial metabolism might help to reduce the illnesses associated with obesity.
Additional Information.
Please access these Web sites via the online version of this summary at
The MedlinePlus encyclopedia has pages on obesity and diabetes (in English and Spanish)
The US Centers for Disease Control and Prevention provides information on all aspects of obesity (in English and Spanish)
The UK National Health Service's health Web site (NHS Direct) provides information about obesity
The International Obesity Taskforce provides information about preventing obesity and on diabetes and obesity
The UK Foods Standards Agency and the United States Department of Agriculture provide online tools and useful advice about healthy eating for adults and children
Information is available for patients and carers from the US National Diabetes Information Clearinghouse on diabetes, including information on insulin resistance
PMCID: PMC2265758  PMID: 18336063
22.  Regulation of bladder muscarinic receptor subtypes by experimental pathologies 
Autonomic & autacoid pharmacology  2006;26(3):311-325.
The M3 muscarinic receptor subtype is widely accepted as the receptor on smooth muscle cells that mediates cholinergic contraction of the normal urinary bladder and other smooth muscle tissues, however, we have found that the M2 receptor participates in contraction under certain abnormal conditions. The aim of this study was to determine the effects of various experimental pathologies on the muscarinic receptor subtype mediating urinary bladder contraction.Experimental pathologies resulting in bladder hypertrophy (denervation and outlet obstruction) result in an up-regulation of bladder M2 receptors and a change in the receptor subtype mediating contraction from M3 towards M2. Preventing the denervation-induced bladder hypertrophy by urinary diversion prevents this shift in contractile phenotype indicating that hypertrophy is responsible as opposed to denervation per se.The hypertrophy-induced increase in M2 receptor density and contractile response is accompanied by an increase in the tissue concentrations of mRNA coding for the M2 receptor subtype, however, M3 receptor protein density does not correlate with changes in M3 receptor tissue mRNA concentrations across different experimental pathologies.This shift in contractile phenotype from M3 towards M2 subtype is also observed in aged male Sprague–Dawley rats but not females or either sex of the Fisher344 strain of rats.Four repeated, sequential agonist concentration response curves also cause this shift in contractile phenotype in normal rat bladder strips in vitro, as evidenced by a decrease in the affinity of the M3 selective antagonist p-fluoro-hexahydro-sila-diphenidol (p-F-HHSiD).A similar decrease in the contractile affinity of M3 selective antagonists (darifenacin and p-F-HHSiD) is also observed in bladder specimens from patients with neurogenic bladder as well as certain organ transplant donors.It is concluded that although the M3 receptor subtype predominately mediates contraction under normal circumstances, the M2 receptor subtype can take over a contractile role when the M3 subtype becomes inactivated by, for example, repeated agonist exposures or bladder hypertrophy. This finding has substantial implications for the clinical treatment of abnormal bladder contractions.
PMCID: PMC3275807  PMID: 16879497
muscarinic receptor subtypes; bladder; hypertrophy; denervation; contraction; ageing; bladder outlet obstruction
23.  Role of Neural NO Synthase (nNOS) Uncoupling in the Dysfunctional Nitrergic Vasorelaxation of Penile Arteries from Insulin-Resistant Obese Zucker Rats 
PLoS ONE  2012;7(4):e36027.
Erectile dysfunction (ED) is considered as an early sign of vascular disease due to its high prevalence in patients with cardiovascular risk factors. Endothelial and neural dysfunction involving nitric oxide (NO) are usually implicated in the pathophysiology of the diabetic ED, but the underlying mechanisms are unclear. The present study assessed the role of oxidative stress in the dysfunctional neural vasodilator responses of penile arteries in the obese Zucker rat (OZR), an experimental model of metabolic syndrome/prediabetes.
Methods and Results
Electrical field stimulation (EFS) under non-adrenergic non-cholinergic (NANC) conditions evoked relaxations that were significantly reduced in penile arteries of OZR compared with those of lean Zucker rats (LZR). Blockade of NO synthase (NOS) inhibited neural relaxations in both LZR and OZR, while saturating concentrations of the NOS substrate L-arginine reversed the inhibition and restored relaxations in OZR to levels in arteries from LZR. nNOS expression was unchanged in arteries from OZR compared to LZR and nNOS selective inhibition decreased the EFS relaxations in LZR but not in OZR, while endothelium removal did not alter these responses in either strain. Superoxide anion production and nitro-tyrosine immunostaining were elevated in the erectile tissue from OZR. Treatment with the NADPH oxidase inhibitor apocynin or acute incubation with the NOS cofactor tetrahydrobiopterin (BH4) restored neural relaxations in OZR to levels in control arteries, while inhibition of the enzyme of BH4 synthesis GTP-cyclohydrolase (GCH) reduced neural relaxations in arteries from LZR but not OZR. The NO donor SNAP induced decreases in intracellular calcium that were impaired in arteries from OZR compared to controls.
The present study demonstrates nitrergic dysfunction and impaired neural NO signalling due to oxidative stress and nNOS uncoupling in penile arteries under conditions of insulin resistance. This dysfunction likely contributes to the metabolic syndrome-associated ED, along with the endothelial dysfunction also involving altered NO signalling.
PMCID: PMC3335073  PMID: 22540017
24.  Spectral analysis of bowel sounds in intestinal obstruction using an electronic stethoscope 
AIM: To determine the value of bowel sounds analysis using an electronic stethoscope to support a clinical diagnosis of intestinal obstruction.
METHODS: Subjects were patients who presented with a diagnosis of possible intestinal obstruction based on symptoms, signs, and radiological findings. A 3M™ Littmann® Model 4100 electronic stethoscope was used in this study. With the patients lying supine, six 8-second recordings of bowel sounds were taken from each patient from the lower abdomen. The recordings were analysed for sound duration, sound-to-sound interval, dominant frequency, and peak frequency. Clinical and radiological data were reviewed and the patients were classified as having either acute, subacute, or no bowel obstruction. Comparison of bowel sound characteristics was made between these subgroups of patients. In the presence of an obstruction, the site of obstruction was identified and bowel calibre was also measured to correlate with bowel sounds.
RESULTS: A total of 71 patients were studied during the period July 2009 to January 2011. Forty patients had acute bowel obstruction (27 small bowel obstruction and 13 large bowel obstruction), 11 had subacute bowel obstruction (eight in the small bowel and three in large bowel) and 20 had no bowel obstruction (diagnoses of other conditions were made). Twenty-five patients received surgical intervention (35.2%) during the same admission for acute abdominal conditions. A total of 426 recordings were made and 420 recordings were used for analysis. There was no significant difference in sound-to-sound interval, dominant frequency, and peak frequency among patients with acute bowel obstruction, subacute bowel obstruction, and no bowel obstruction. In acute large bowel obstruction, the sound duration was significantly longer (median 0.81 s vs 0.55 s, P = 0.021) and the dominant frequency was significantly higher (median 440 Hz vs 288 Hz, P = 0.003) when compared to acute small bowel obstruction. No significant difference was seen between acute large bowel obstruction and large bowel pseudo-obstruction. For patients with small bowel obstruction, the sound-to-sound interval was significantly longer in those who subsequently underwent surgery compared with those treated non-operatively (median 1.29 s vs 0.63 s, P < 0.001). There was no correlation between bowel calibre and bowel sound characteristics in both acute small bowel obstruction and acute large bowel obstruction.
CONCLUSION: Auscultation of bowel sounds is non-specific for diagnosing bowel obstruction. Differences in sound characteristics between large bowel and small bowel obstruction may help determine the likely site of obstruction.
PMCID: PMC3435785  PMID: 22969233
Bowel sounds; Intestinal obstruction; Spectral analysis; Electronic stethoscope
25.  Increase in neurokinin-1 receptor-mediated colonic motor response in a rat model of irritable bowel syndrome 
AIM: Irritable bowel syndrome (IBS) is a functional bowel disorder. Its major symptom is bowel dysmotility, yet the mechanism of the symptom is poorly understood. Since the neurokinin-1 receptor (NK1R)-mediated signaling in the gut is important in the control of normal bowel motor function, we aimed to investigate whether the NK1R-mediated bowel motor function was altered in IBS, using a rat IBS model that was previously reported to show colonic dysmotility in response to restraint stress.
METHODS: IBS symptoms were produced in male Sprague-Dawley rats by inducing colitis with acetic acid. Rats were left to recover from colitis for 6 d, and used for experiments 7 d post-induction of colitis. Motor activities of distal colon were recorded in vitro.
RESULTS: The contractile sensitivity of isolated colon to a NK1R agonist [Sar9,Met(O2)11]-substance P (1-30 nmol/L) was higher in IBS rats than that in normal rats. After the enteric neurotransmission was blocked by tetrodotoxin (TTX, 1 μmol/L), the contractile sensitivity to the NK1R agonist was increased in normal colon but not in IBS rat colon. The NK1R agonist-induced contraction was not different between the two groups when the agonist was challenged to the TTX-treated colon or the isolated colonic myocytes. A nitric oxide synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, 100 μmol/L) augmented the NK1R agonist-induced contraction only in normal rat colon.
CONCLUSION: These results suggest that the NK1R-meidated colonic motor response is increased in IBS rats, due to the decrease in the nitrergic inhibitory neural component.
PMCID: PMC4205409  PMID: 15633223
Irritable bowel syndrome; Neurokinin-1 receptor

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