可乐定对雌激素预处理的大鼠离体子宫的抑制作用。

The inhibitory effect of clonidine on the oestrogen-primed rat isolated uterus.

作者信息

Goyal R K, Dave K C, Verma S C

出版信息

J Auton Pharmacol. 1983 Sep;3(3):213-7. doi: 10.1111/j.1474-8673.1983.tb00537.x.

DOI:10.1111/j.1474-8673.1983.tb00537.x

Abstract

The investigation was undertaken to study the mechanism of the inhibitory effects of clonidine on the oestrogen-primed rat isolated uterus. Clonidine produced dose-dependent relaxations of the rat isolated uterus which were competitively blocked by yohimbine but not by prazosin. Metiamide, a specific H2-histamine receptor antagonist, inhibited clonidine-induced responses only at a high concentration (1.0 X 10(-6)M). Propranolol, a beta-adrenoreceptor antagonist produced competitive antagonism of the clonidine responses. Like clonidine, noradrenaline also produced dose dependent relaxations of the rat isolated uterus. The responses to noradrenaline were not antagonized by either prazosin or yohimbine but were competitively antagonized by propranolol. The responses to clonidine were significantly inhibited by reserpine pretreatment (5 mg/kg; i.p., 24 h before) whilst responses to noradrenaline were significantly increased by this treatment. It is concluded that clonidine inhibits the uterus via an action on alpha 2-adrenoreceptors and possibly also to a lesser extent on H2-histamine receptors, leading ultimately to release of noradrenaline from endogenous stores which causes relaxation by acting on beta-adrenoreceptors.

摘要

进行该研究以探讨可乐定对雌激素预处理的大鼠离体子宫产生抑制作用的机制。可乐定可使大鼠离体子宫产生剂量依赖性舒张，这种舒张作用可被育亨宾竞争性阻断，但不能被哌唑嗪阻断。甲硫咪胺，一种特异性H2组胺受体拮抗剂，仅在高浓度（1.0×10⁻⁶M）时抑制可乐定诱导的反应。普萘洛尔，一种β肾上腺素能受体拮抗剂，对可乐定的反应产生竞争性拮抗作用。与可乐定一样，去甲肾上腺素也可使大鼠离体子宫产生剂量依赖性舒张。哌唑嗪或育亨宾均不能拮抗对去甲肾上腺素的反应，但普萘洛尔可竞争性拮抗该反应。利血平预处理（5mg/kg；腹腔注射，提前24小时）可显著抑制对可乐定的反应，而该处理可使对去甲肾上腺素的反应显著增强。结论是，可乐定通过作用于α2肾上腺素能受体抑制子宫，并且可能在较小程度上也作用于H2组胺受体，最终导致内源性储存的去甲肾上腺素释放，通过作用于β肾上腺素能受体引起舒张。