Tag: Methacholine

Contractile actions of histamine are mediated directly via stimulation of Hx-histamine receptors on airway smooth muscle and, in part, indirectly via stimulation of vagal reflex causing release of acetylcholine at the parasympathetic nerve endings. Inhibition of histamine-induced bronchoconstriction by the anticholinergic agent, ipratropium bromide, in our normal subjects is consistent with this concept. Thus, it […]

Our results demonstrate differences between normal and asthmatic subjects in terms of agonist-agonist interaction. Whereas in normal subjects prior muscarinic stimulation suppressed the histamine-induced bronchoconstriction, no such suppression was observed in subjects with asthma. It is possible that lack of suppressive action of methacholine on histamine-induced bronchoconstriction in asthmatic subjects may be related to two […]

Our in vivo results are consistent with the in vitro findings of Ishii and Kato10 who observed suppression of histamine-induced contraction of guinea pig ileum by prior exposure of the tissues to methacholine. They also observed that the suppressive action of methacholine on subsequent histamine-induced contraction was specific, as neither methacholine nor histamine exposure had […]

Effect of Prior Muscarinic Receptor Stimulation on Histamine and Methacholine-induced Bronchoconstriction In the normal group, prior muscarinic receptor stimulation with methacholine caused a rightward shift in the histamine dose-response curve in most of the subjects and a significant increase in histamine PD.50 (Fig 1 and 2). The mean ± SE histamine PD^ on a control […]

Experimental Protocol Each subject was studied on five occasions separated by at least 72 h. On experiment day 1, after obtaining baseline pulmonary (unction test results, a control bronchial provocation test with histamine was performed to establish PD*, to histamine. Normal subjects in whom PDg„ was not achieved even with 5 mg/ml concentration of histamine […]

Subjects Fifteen nonsmoker subjects (ten men and five women) without a recent history of upper respiratory tract infection were included in the study. Six subjects had a history of mild asthma; their ages ranged from 25 to 52 years (mean 37). The remaining nine subjects had no personal or family history of atopy. Their ages […]

Various types of agonists are capable of contracting the airway smooth muscle through different mechanisms of action.1 Among these agents, histamine and methacholine are the most widely used in the investigation of airway hyperreactivity. The pharmacodynamic properties of these agents have shown that histamine acts through H1 and H2 receptors, whereas methacholine stimulates muscarinic receptors […]

Our study confirms the finding of one other recently reported comparison of parent- and child-completed questionnaires in another country and in older children. Among 271 13-to 14-year-old children in Germany, wheezing in the past year was reported on both questionnaires in 12.1%, by the parent but not the child in 8.3%, by the child but […]

The relatively low sensitivity of the methacholine challenge with regard to a history of milder wheezing symptoms (not diagnosed as asthma) requires comment. Wheezing might occur in association with variable airflow limitation when methacholine airway responsiveness is normal if the stimulus to wheezing is strong, such as a severe reaction to an allergen or chemical […]

This study has documented in a small pilot sample the occurrence of symptoms consistent with asthma and of airway responsiveness to methacholine among a sample population of children aged eight to 10 years. The group of 229 children undertaking all investigations was representative of the full cluster sample selected. The estimated prevalences of both physician-diagnosed […]