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1.  Urokinase Plasminogen Activator Regulates Pulmonary Arterial Contractility and Vascular Permeability in Mice 
The concentration of urokinase plasminogen activator (uPA) is elevated in pathological settings such as acute lung injury, where pulmonary arterial contractility and permeability are disrupted. uPA limits the accretion of fibrin after injury. Here we investigated whether uPA also regulates pulmonary arterial contractility and permeability. Contractility was measured using isolated pulmonary arterial rings. Pulmonary blood flow was measured in vivo by Doppler and pulmonary vascular permeability, according to the extravasation of Evans blue. Our data show that uPA regulates the in vitro pulmonary arterial contractility induced by phenylephrine in a dose-dependent manner through two receptor-dependent pathways, and regulates vascular contractility and permeability in vivo. Physiological concentrations of uPA (≤1 nM) stimulate the contractility of pulmonary arterial rings induced by phenylephrine through the low-density lipoprotein receptor–related protein receptor. The procontractile effect of uPA is independent of its catalytic activity. At pathophysiological concentrations, uPA (20 nM) inhibits contractility and increases vascular permeability. The inhibition of vascular contractility and increase of vascular permeability is mediated through a two-step process that involves docking to N-methyl-d-aspartate receptor–1 (NMDA-R1) on pulmonary vascular smooth muscle cells, and requires catalytic activity. Peptides that specifically inhibit the docking of uPA to NMDA-R, or the uPA variant with a mutated receptor docking site, abolished both the effects of uPA on vascular contractility and permeability, without affecting its catalytic activity. These data show that uPA, at concentrations found under pathological conditions, reduces pulmonary arterial contractility and increases permeability though the activation of NMDA-R1. The selective inhibition of NMDAR-1 activation by uPA can be accomplished without a loss of fibrinolytic activity.
PMCID: PMC3262683  PMID: 21617202
urokinase; NMDA-R; lung; permeability
2.  Regulation of Airway Contractility by Plasminogen Activators through N-Methyl-D-Aspartate Receptor–1 
Reactive airway disease is mediated by smooth muscle contraction initiated through several agonist-dependent pathways. Activation of type 1 N-methyl-D-aspartate receptors (NMDA-R1s) by plasminogen activators (PAs) has been linked to control of vascular tone, but their effect on airway smooth muscle contractility has not previously been studied to our knowledge. We observed that NMDA-R1s are expressed by human airway smooth muscle cells and constitutively inhibit the contraction of isolated rat tracheal rings in response to acetylcholine (Ach). Both tissue-type PA (tPA) and urokinase-type PA (uPA) bind to NMDA-R1 and reverse this effect, thereby enhancing Ach-induced tracheal contractility. Tracheal contractility initiated by Ach is reduced in rings isolated from tPA−/− and uPA−/− mice compared with their wild-type counterparts. The procontractile effect of uPA or tPA was mimicked and augmented by the nitric oxide synthase inhibitor, l-NAME. uPA and tPA further enhanced the contractility of rings denuded of epithelium, an effect that was inhibited by the NMDA-R antagonist, MK-801. Binding of PAs to NMDA-R1 and the subsequent activation of the receptor were inhibited by PA inhibitor type 1, by a PA inhibitor type 1–derived hexapeptide that recognizes the tPA and uPA docking domains, as well as by specific mutations within the docking site of tPA. These studies identify involvement of PAs and NMDA-R1 in airway contractility, and define new loci that could lead to the development of novel interventions for reactive airway disease.
PMCID: PMC2993090  PMID: 20097831
tissue plasminogen activator; urokinase NMDA receptor; lungs
3.  A simple approach discriminating cardio­safe drugs from toxic ones 
Bioinformation  2009;3(9):389-393.
More than 130 FDA-approved drugs have been identified for now to prolong the QT interval and possibly lead to sudden cardiac death. Due to their toxic effect, some of these drugs have been withdrawn from the pharmaceutical market. In this study, we have formulated few rules to assess the ability to prolong QT interval and thereby discriminate between cardiotoxic and -safe drugs. These rules have clearly determined that cardio-toxic drugs are more likely to obey Lipinski rule of 5 and Oprea lead-like rule. Moreover, the cardio-toxic drugs have been found to have in common values of -0.5 to 6.5 log P, 1-5 nitrogen atoms, up to 4 oxygen atoms, 5-27 hydrophobic atoms, and 15-53 single bonds. Matthews Correlation Coefficient with the value of 0.6 was also attained and nearly 96% of the cardio-toxic drugs were successfully covered. Thus, despite the simplicity of this methodology, we have obtained interesting and informative results. The proposed set of these simple rules could be employed to infer cardio-toxicity or -safety for current and potential drugs. The present study will have important impact on decision making in the fields of drug development, molecule screening in biological assays, and other applications as well.
PMCID: PMC2732033  PMID: 19759813
Long QT Syndrome; cardio-toxic drug; prediction model
4.  Effects of the SOD mimic nitroxide 3-carbamoyl-PROXYL on oxidative stress markers and endothelial dysfunction in streptozotocin-induced diabetic rats 
To evaluate the effects of 3-carbamoyl-PROXYL (CP), a stable superoxide dismutase (SOD) mimic compound, on oxidative stress markers and endothelial dysfunction in diabetic rats.
Rats were made diabetic by a single vein injection of streptozotocin (65 mg/kg) and diabetes was verified by the existence of excessive hyperglycemia a week after the treatment. Control and diabetic rats received vehicle or drug for eight weeks, after which the vascular tissue was examined for relaxation and oxidative stress markers.
Diabetic rats showed increased vascular levels of superoxide that were accompanied by increased tissue levels of the oxidative stress markers malondialdehyde (MDA) and 8-iso-prostaglandin F2α (8-ISO). The vasorelaxant as well as the cyclic guanosine 5′-monophosphate (cGMP)-producing effects of acetylcholine (ACh) and nitroglycerine were reduced in diabetic rats. Treatment of diabetic rats with CP (50 mg/kg intraperitoneally, bid) abolished not only the differences in superoxide, MDA and 8-ISO levels, but also the differences in the relaxation and cGMP responses of vascular tissue between control and diabetic rats to both ACh and nitroglycerine.
These results support the involvement of reactive oxygen species in mediation of diabetes-induced endothelial dysfunction in vivo, and provide the rationale for the potential use of SOD mimics in the treatment of diabetes.
PMCID: PMC2719166  PMID: 19649229
cGMP; Endothelial dysfunction; Isoprostanes; Lipid peroxidation; Nitric oxide; Relaxation; Superoxide

Results 1-4 (4)