EFFECTS OF RHYNCHOPHYLLlNE ON CONTRACTILITY OF ISOLATED GUINEA-PIG TAENIA COLI / 中国药理学通报

ABSTRACT

The contractions induced by acetylcholine or Ca2 + after high-K+ depolarization in isolated guinea-pig taenia coli were markedly inhibited by rhynchophylline (Rhy). It caused rightward displacement of the dose-response curve for CaCl2 & significantly depressed the maximal response, showing a non-competitive antigonism. The pD'2 value of Rhy was 4.95?0.05. In Ca2+-free solution,Rhy similar to verapamil (Ver), inhibited acetylcholine-induced contraction of guinea-pig taenia coli, which is dependent on Ca2+ released from an intracellular store. After Ca2+ concentration in bath solution was restored, Ver did not influence the contraction of taenia coli depending on extracellular Ca2 + , However 40 ?mol/L Rhy could exhibit marked inhibitory action.