Elsevier

Pulmonary Pharmacology

Volume 6, Issue 3, September 1993, Pages 171-175
Pulmonary Pharmacology

Regular Article
A Comparative Study of the Effects of Citric Acid, Capsaicin and Resiniferatoxin on the Cough Challenge in Guinea-pig and Man

https://doi.org/10.1006/pulp.1993.1023Get rights and content

Abstract

Summary: The cough response following inhalation challenge with the sensory nerve irritant resiniferatoxin was compared with that of capsaicin and citric acid in guinea-pig and man. Capsaicin and citric acid gave comparable dose-response curves in the two species. The mean (± SEM) concentration producing five coughs in man was 141.3 (1.3) mM (n=10) for citric acid and 2.8 (1.3) μM (n=10) for capsaicin. Those for the guinea-pig were 74.1 (1.2) mM (n=10) for citric acid and 6.0 (2.4) μM (n=10) for capsaicin. Resiniferatoxin was active at a lower concentration than either citric acid or capsaicin and maximal tolerable cough response was achieved at concentrations of 3 μM (n=5) in guinea-pig and 300 nM (n=1) in man. The cough response to resiniferatoxin was greatly prolonged in both guinea-pig and man. Resiniferatoxin, like capsaicin, caused respiratory distress in the guinea-pig which is linked to bronchoconstriction. Resiniferatoxin probably causes cough by stimulation of capsaicin sensitive neurones.

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