纳洛酮对大鼠心室肌细胞L型钙电流的影响

Effect of naloxone on L-type calcium current in isolated rat ventricnlar myocytes

目的评价纳洛酮对大鼠心室肌细胞L型钙电流（ICa-L）的影响。方法采用急性酶解法分离SD大鼠单个心室肌细胞，以全细胞膜片钳技术测定ICa-L。纳洛酮采用累积给药法，记录不同浓度（20和100ug／ml）纳洛酮作用下心室肌细胞ICa-L和给药前、后半激活电压。结果20和100ug／ml的纳洛酮分别使L型钙通道峰电流强度从给药前（341±30）pA降至（270±23）pA和（173±21）pA，与20μg／ml纳洛酮相比，100μg／ml纳洛酮给药后L型钙通道峰电流强度降低（P〈0．05）。20和100μg／ml纳洛酮给药前、后半激活电压比较差异无统计学意义（P〉0．05）。结论纳洛酮可抑制大鼠心室肌细胞L型钙通道，具有心室肌负性肌力作用。

Objective To evaluate the effect of naloxone on L-type calcium current （Ica-L） in isolated rat ventricular myocytes. Methods Adult SD rats of both sexes aged 8 weeks weighing 200-250 g were used in this study. Single cardiac ventrieular myoeytes were enzymatieally isolated from SD rats. Ica-L was measured in ventricular myocytes and recorded using whole cell patch-clamp technique. Different concentrations （20 and 100 μg/ml） of naloxone were added to the eardiomyocytes. The effect of naloxone on Ica-L was evaluated. Results The peak current of Ica-L was inhibited by naloxone in a concentration-dependent manner. Naloxone had no significant effect on steady-state activation curve. Conclusion Naloxone inhibits the L-type calcium channel of ventricular myocytes and exerts negative effect on ventricutar muscle function.