异丙酚舒张血管平滑肌的作用机制

目的:检测异丙酚(Propofol)影响大鼠主动脉平滑肌细胞(ASMC)内游离钙离子浓度(Ca~(2 )]i)作用与影响三磷酸肌醇(inositol 1,4,5-triphosphate,IP_3)合成作用,探讨异丙酚舒张血管平滑肌的作用机制。方法:应用荧光分光光度法,通过荧光剂Fura-2/AM负荷,检测原代培养的ASMC内Ca~(2 )]i的水平;应用~3H]肌醇三磷酸测试系统,通过同位素竞争蛋白结合实验,检测ASMC合成IP_3水平。结果:(1)异丙酚与ASMC共同培养72小时后,检测到ASMC的Ca~(2 )]i基线水平较对照组轻度降低,异丙酚可剂量依赖性抑制去甲肾上腺素(NE)、5-羟色胺(5-HT)引起的Ca~(2 )]i升高作用;(2)当细胞外液无钙时或钙通道阻滞剂维拉帕米(Virapamil)存在时,异丙酚抑制Ca~(2 )]i升高作用被部分减弱,但不被取消;(3)异丙酚可剂量依赖性地抑制NE、5-HT的促进IP_3合成作用。结论:异丙酚舒张血管平滑肌作用与抑制IP_3介导的细胞内钙释放作用(IICR)机制密切相关。

Mechanism of Inhibition of propofol on intracellular calcium increase in aortic smooth muscle cells

Objective:To test the effects of propofol on intracellular calcium free concentration (Ca~(2 )]i) and inositol 1,4,5-triphosphate (IP_3) biological synthesis induced by norepinephrine (NE) and 5-hydroxytryptamine (5-HT) in aortic smooth muscle cells (ASMC)of rats for the mechanism of relaxtion of propofol on vascular smooth muscle.Method: Using the flurospectrophotometry and Fura-2/AM loading method,the changes of Ca~(2 )]i levels in primary culture ASMC were measured,and using the specific, IP_3 assay system and isotope radioactive protein binding experiment IP_3 production levels in aortic smooth muscle were measured. Result:The baselines of Ca~(2 )]i was decreased when primary culture ASMC was pretreated with propofol in 72 hours. Propofol inhibited Ca~(2 )]i increase induced by NE and 5-HT in dose-dependent way. With extracellular calcium free or calcium channel blocker(Verapamil),inhibition of propofol on NE and 5-HT increasing Ca~(2 )]i levels were decreased,but could not be cancelled. Propofol depressed IP_3 biological synthesis induced by NE and 5-HT in dose-dependent way. Conclusion:Relaxation of propofol on aortic smooth muscle is closely related to inhibiting IP_3- induced calcium release to decrease intracellular calcium concentration.