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Pulm Pharmacol. 1993 Sep;6(3):171-5.

A comparative study of the effects of citric acid, capsaicin and resiniferatoxin on the cough challenge in guinea-pig and man.

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University Department of Medicine, Royal Hallamshire Hospital, Sheffield, UK.


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) microM (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) microM (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 microM (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.

[Indexed for MEDLINE]

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