【摘要】 本实验观察了可乐定对自家血恒速灌流的毁脑脊髓大鼠（pithed rat）后肢血管平滑肌的作用和该处突融后膜两种α受体亚型的存在。可乐定引起灌流压（PP）升高,呈剂量依赖关系,但效能远比选择性α₁受体激动剂苯福林低。对预先用利血平处理的大鼠,可乐定的作用被显著增强。高度选择性的α₁受体阻断剂哌唑嗪0.3mg/kg iv可部分阻断可乐定100μg ia的作用,增加哌唑嗪的剂量并不能进一步增加对可乐定的阻断作用。对于哌唑嗪不能阻断的部分,α₁受体阻断剂育亨宾却能表现出十分明显的抑制作用。这些结果提示在大鼠后肢血管平滑肌突触后膜上存在有α₁和α₂肾上腺素受体,但α₁受体似乎占优势。更多还原

【Abstract】 The effects of clonidine on vascular smooth muscle in the perfused hindquarters of pithed rats and the existence of postsynaptic α-adrenoceptor subtypes on these sites were observed. Clonidine dose-depen-dently increased perfused pressure, but the efficacy was much smaller than that of phenylephrine,a selective α1-adrenoceptor agonist. The effects of clonidine was significantly potentiated by pretreatment of reset-pine. Prazosin, a highly selective α2-adrenoceptor blocker,did not completely antagonize the elevation ofperfused pressure induced by clonidine 100μg ia,but the prazosin-resis-tant part of the effect of clonidine was significantly inhibited by yo-himbine, an α2-adrenoceptor blocker. These results suggest that the hind-quarter vascular smooth muscle of rat has α1-and α2-adrenoceptors, and α1-receptor seems to be dominant.更多还原