Histamine receptors in the bronchial musculature and vasculature of the dog.

Participation of histamine H1- and H2-receptors in the bronchial musculature and vasculature of the dog was investigated by using the method for evaluating airway responses. A peristaltic pump and a Starling pneumatic resistance were used for a constant pressure perfusion. Dogs given 0.1 - 10 micrograms histamine by a close intraarterial injection showed increases in ventilation overflow (bronchoconstriction) and in blood flow (bronchial vasodilatation) in a dose-dependent manner. The bronchoconstriction produced by histamine was antagonized strongly by chlorpheniramine, a H1-receptor antagonist, but not modified by cimetidine, a H2-receptor antagonist. The bronchial vasodilation produced by histamine was antagonized by both chlorpheniramine and cimetidine. These results suggest that histamine evokes bronchoconstriction through H1-receptors and bronchial vasodilatation through H1- and H2-receptors.