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

Abstract

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.