d‐Arg[Hyp³‐Thi⁵‐d‐Tic⁷‐Tic⁸]‐bradykinin, a potent antagonist of smooth muscle BK₂ receptors and BK₃ receptors

d‐Arg[Hyp³‐Thi⁵‐d‐Tic⁷‐Tic⁸]‐bradykinin (NPC 16731) inhibited bradykinin (BK) binding and BK‐induced contraction in guinea‐pig ileum, being markedly more potent than d‐Phe⁷‐BK analogues as a BK₂ receptor antagonist. In isolated trachea NPC 16731, unlike other BK₂ antagonists, inhibited BK binding and BK‐induced contraction, and ⁴⁵Ca²⁺ efflux in tracheal smooth muscle cells. That NPC 16731 potently inhibits BK effects in trachea provides further evidence for the existence of the airway BK₃ receptor. 1991 British Pharmacological Society