Inhibition of bradykinin‐induced bronchoconstriction in the guinea‐pig by a synthetic B2 receptor antagonist

1 Intravenous bradykinin (Bk) elicited bronchoconstriction in the anaesthetized ventilated guinea‐pig which was not mimicked by the B1 receptor agonist, des‐Arg9‐Bk. 2 Bradykinin‐induced bronchoconstriction was inhibited by the B2 receptor antagonist B4881, but not by the B1 receptor antagonist des‐Arg9‐Leu8‐Bk. The effect of B4881 was short‐lived. 3 The B2 receptor antagonist as B4881 was selective for bradykinin as B4881 did not significantly inhibit bronchoconstriction induced by i.v. bombesin, platelet activating factor, acetylcholine, histamine or vagal stimulation. 4 These results suggest that bradykinin‐induced bronchoconstriction in the guinea‐pig is via activation of a B2 receptor population and that B4881 is a selective B2 antagonist that may be useful for investigating the involvement of bradykinin in the lung.