钩藤碱对大鼠离体子宫收缩反应的影响

本文观察到Rhy对催产素和高K~+去极化后Ca~(2+)引起的大鼠离体子宫收缩均有抑制作用,前一作用可被Ca~(2+)所对抗。CaCl_2量效曲线显示,Rhy对其呈非竞争性拮抗。在无Ca~(2+)高K~+液中,Rhy10μM抑制催产素依赖细胞内Ca~(2+)引起的收缩,而Rhy 40μM除加强这一作用外,对催产素依赖细胞外Ca~(2+)的收缩亦有抑制作用。

Effects of rhynchophylline on contraction of isolated rat uterus

The effects of rhyncho phylline (Rhy) on isotonic contraction of isolated rat uterus were investigated.The isolated rat uterus contractioninduced by Ca2+ (0.5 mM) after high K+de polarization was markedly relaxed by Rhy 10 μM, and verapamil (Ver) 10 nM, 50 nM. The percentages of inhibition are 74.6 %, 100.2%, 45.8% and 90.3%, respectively.Pre-incubation for 30 min with Rhy 10 μM, 50 μM, and Ver 10 nM, 50 nM induced dose-dependent rightward displacements of the concentration-response curves for Ca2+ (0.01-10 mM) and the maximal responses to Ca2+ were depressed, showing a non-competitive antagonism. The pD2 values of Rhy and Ver were 4.6 and 7.2, respectively. The effect of Ver was stronger than that of Rhy.In normal physiological solution, the isolated rat uterus contraction induced by oxytocin (Oxy, 3 mU/ml) were inhibited dose-dependently by Rhy (7.5-50 μM). This depression was immediately reversed by addition of 2 mM Ca2+ to the bath solution.A further study showed that the Oxy induced uterus contraction could be divided into two components: the Cai-dependent contraction (it occured in high K+-Ca2+ free depolarized solution) and Ca0-dependent contraction (a further contraction after the Ca2+ concentration in the bath solution was restored). The Cai -dependent contraction was depressed obviously by Rhy 10μM and Ver 10 nM, 50 nM but the Cao-dependent one was inhibited only by Rhy 40μM.These results indicate that Rhy could be a calcium antagonist.