瑞芬太尼对人肠系膜小动脉平滑肌细胞大电导钙激活钾通道的影响

Effects of remifentanil on large-conductance Ca2 ＋ -activated potassium channels in human mesenteric arterial smooth muscle cells

目的 观察瑞芬太尼对人肠系膜小动脉平滑肌细胞大电导钙激活钾通道（BKCa）的影响,探讨其扩张血管的机制.方法 酶消化法急性分离人肠系膜小动脉平滑肌细胞,采用全细胞膜片钳技术,＋80 mV钳制电压下记录不同浓度瑞芬太尼（1.2、4.8、19.4、77.4和310.0 nmol/L）给药后人肠系膜小动脉平滑肌细胞BKCa电流及达峰时间,计算BKCa激活率.结果 瑞芬太尼可激活BKCa,使电流密度-电压曲线上移,激活电压不变;随瑞芬太尼浓度升高,BKCa激活率逐渐升高（P＜0.01）,19.4 nmol/L时BKCa激活率趋于稳定;各浓度瑞芬太尼给药后BKCa电流达峰时间比较差异无统计学意义（P＞0.05）;瑞芬太尼浓度与BKCa激活率成对数曲线关系,其半数最大激活效应浓度为（118±7）nmol/L.结论 瑞芬太尼浓度依赖性地激活人肠系膜小动脉平滑肌细胞BKCa,该作用可能是其产生扩张血管作用的机制.

Objective To investigate the effects of remifentanil on large-conductance Ca2＋ -activated potassium channel （BKCa） in human mesenteric arterial smooth muscle cells （MASMCs） and the mechanism of the vasorelaxant effect of remifentanil. Methods Human MASMCs were obtained freshly by the method of enzymolysis. BKCa current （IBKCa） was recorded by the whole-cell patch clamp technique. The changes in IBKC. produced by different concentrations of remifentanil （1.2, 4.8, 19.4, 77.4 and 310.0 nmol/L） with the holding potential of ＋ 80 mV were observed. BKCa activation rate was calculated. Results Remifentanil significantly increased IBKCa,moved Ⅰ-Ⅴ curve upward and had no effect on the threshold of activation for IBKCa . With the increase in the concentration of remifentanil, BKCa activation rate increased gradually （P 〈 0.01）, and it remained stable when the concentration reached 19.4 nmol/L. There was no significant difference in the peak time of IBKCa after different concentrations of remifentanil were given （P 〉 0.05）. Logarithmic curve was found to suit the relationship between the concentration of remifentanil and BKCa activation rate and the IC50 concentration was （118 ± 7） nmol/L. Conclusion Remifentanil results in vasorelaxation by activating BKCa in MASMCs in a concentration-dependent manner.