[Tachyphylaxis induced by repeated inhalation of bradykinin in asthmatic patients]

Bradykinin is a nonapeptide, which may act as a mediator in asthma since it is generated upon nasal immunological challenge in vivo and it has been shown to induce some asthma-like symptoms. In vitro studies suggest that refractoriness following bradykinin challenge may be due to release of contractile tachykinins. In this study it was shown that repeated bronchial challenge with bradykinin in atopic asthmatic subjects induced loss of response to the nonapeptide. Once achieved, reduced bradykinin responsiveness was not accompanied by loss of airways response to histamine. Moreover, repeated challenge with histamine failed to produce a significant loss of airways response to this agonist. In conclusion, either the depletion of contractile tachykinins or the down-regulation at the level of specific kinin receptors might account for the refractoriness following repeated inhalation of bradykinin in asthmatic subjects.