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1.  Effect of hyperthyroidism on bronchial reactivity in non-asthmatic patients. 
Thorax  1989;44(7):603-604.
Thyrotoxicosis may be associated with deterioration in asthma. To determine whether bronchial reactivity to histamine is increased in hyperthyroidism 10 thyrotoxic non-asthmatic patients were assessed before and after treatment of their thyrotoxicosis. No significant change in bronchial reactivity was found after treatment.
PMCID: PMC461977  PMID: 2772862
2.  Effect of verapamil and sodium cromoglycate on leukotriene D4 induced bronchoconstriction in patients with asthma. 
Thorax  1986;41(10):753-758.
Leukotriene D4 (LTD4) may be an important mediator in asthma. The effect of verapamil and sodium cromoglycate on LTD4 induced bronchoconstriction has been examined in seven patients with asthma. The bronchoconstrictor response to increasing concentrations of inhaled LTD4 (0.0032-50 micrograms/ml) was assessed by measuring changes in FEV1, specific airways conductance, and flow rate at 30% of vital capacity (V30(p)). Results were expressed as the provocation concentration (PC) producing a 10% fall in FEV1 (PC10FEV1), a 35% fall in specific airways conductance (PC35SGaw), and a 30% fall in flow at 30% of vital capacity (PC30 V30(p)). Neither verapamil nor cromoglycate inhibited LTD4 induced bronchoconstriction in asthmatic subjects. These results suggest that in asthmatic patients LTD4 induced bronchoconstriction is not mediated via verapamil or cromoglycate sensitive mechanisms.
PMCID: PMC460470  PMID: 3097863
3.  In vitro and in vivo effect of verapamil on human airway responsiveness to leukotriene D4. 
Thorax  1986;41(1):12-16.
The mechanism by which leukotriene D4 (LTD4) induces airway narrowing in man is unclear. We have investigated this by examining the effect of the calcium channel blocker verapamil on the sensitivity of in vitro preparations of human bronchi to LTD4 and methacholine, and on the bronchoconstriction induced in normal subjects by these agonists in vivo. In vitro smooth muscle sensitivity was assessed by the concentration of LTD4 and methacholine causing a 50% of maximum contraction (EC50) and as the maximum tension generated. Verapamil did not alter baseline tension or the response to LTD4 but did inhibit contractile responses to methacholine. In vivo studies were performed in six normal subjects; they inhaled increasing concentrations of LTD4 (0.4-50 micrograms/ml) or methacholine (2-64 mg/ml). Airway responsiveness in vivo was expressed as the provocation concentration (PC) of agonist producing a 35% fall in specific airways conductance (PC35sGaw) and a 30% fall in flow at 30% of vital capacity (PC30 V30(p)). Verapamil did not alter baseline sGaw or V30(p). One subject did not respond to LTD4 on either day. In contrast to the in vitro results, verapamil produced a greater than 10 fold reduction in LTD4 induced bronchoconstriction, but had no effect on methacholine induced bronchoconstriction. These results suggest that in normal subjects bronchoconstriction induced by inhaled LTD4 is due to a combination of direct and indirect mechanisms.
PMCID: PMC460245  PMID: 3518128
4.  Airway responsiveness to histamine in man: effect of atropine on in vivo and in vitro comparison. 
Thorax  1985;40(4):261-267.
Airway responsiveness to histamine in man may be determined by the smooth muscle sensitivity to histamine or to the interaction between vagal nerve input and smooth muscle sensitivity. We have compared in vivo responsiveness to histamine with in vitro smooth muscle sensitivity to histamine in 20 non-asthmatic patients and one asthmatic patient undergoing thoracic surgery. Histamine responsiveness was assessed in the first 10 non-asthmatics without atropine pretreatment, in the second 10 after atropine pretreatment, and in the asthmatic patient both with and without atropine. In vivo responsiveness was also measured in 10 normal subjects and 10 asthmatic patients not undergoing surgery. Results were expressed as the provocation concentration (PC) causing a decrease in FEV1 of 20% (PC20FEV1) and in specific airways conductance of 35% (PC35SGaw), and in terms of maximal expiratory flow at 35% vital capacity, measured from the partial (V35(P] and complete (V35(C] flow volume curves of 35% (PC35V35(P); PC35V35(C]. In vitro smooth muscle sensitivity to histamine of bronchial tissue obtained at thoracotomy was expressed as the concentration causing a 50% maximum contraction (EC50) and as the maximum tension generated. There was considerable variation between patients in the in vivo responsiveness but a relatively narrow range for in vitro responses. There was no significant correlation between in vivo responsiveness, either with or without atropine pretreatment, and in vitro results. The asthmatic patient showed hyperresponsiveness in vivo but but not in vitro. These results suggest that in vitro airway smooth muscle sensitivity to histamine is not the sole determinant of in vivo airway responsiveness and that this lack of relationship is not explained by the influence of vagal nerve input on in vivo measurements. The results in the asthmatic patient suggest that airway hyperresponsiveness may be an in vivo phenomenon which is not related to a primary abnormality of airway smooth muscle.
PMCID: PMC460043  PMID: 4023976
5.  Comparison of in vivo airway responsiveness and in vitro smooth muscle sensitivity to methacholine in man. 
Thorax  1984;39(11):837-843.
Airway responsiveness to methacholine varies between normal people and is increased in patients with asthma. The importance of airway smooth muscle sensitivity in determining in vivo responsiveness is unknown. We have examined this question by comparing in vivo airway responsiveness with in vitro airway smooth muscle sensitivity to methacholine in 10 patients undergoing thoracic surgery. In vivo responsiveness was determined by administration of inhalations of doubling concentrations of methacholine. Results were expressed as the provocation concentration (PC) causing a decrease in forced expiratory volume in one second of 20% (PC20FEV1), specific airway conductance of 35% (PC35SGaw), and maximal expiratory flow at 35% vital capacity, measured for the partial (V35(p)) and complete (V35(c)) flow volume curves, of 35% (PC35V35(p); PC35V35(c)). In vitro airway smooth muscle sensitivity was determined from specimens obtained at thoracotomy. Log dose-response curves to methacholine were constructed and the concentration causing a 50% maximum contraction (EC50) was derived. There were differences between patients for both in vivo airway responsiveness and in vitro smooth muscle sensitivity to methacholine. There were no significant relationships between the in vivo and in vitro measurements. The results suggest that factors other than solely the sensitivity of smooth muscle must determine in vivo airway responsiveness to methacholine.
PMCID: PMC459934  PMID: 6390773

Results 1-5 (5)