银杏叶提取物对豚鼠心室肌细胞动作电位及L型钙离子通道的影响

Effects of Ginkgo biloba extract on action potential and L-type calcium channel in guinea pig's ventricular myocytes

目的 :观察银杏叶提取物 (EGB)对豚鼠心室肌细胞动作电位和L 型钙通道的影响。方法 :采用全细胞膜片钳技术的电流钳记录动作电位和电压钳记录L 型钙离子通道电流 (ICa L)。结果 :银杏叶提取物 (原液含银杏黄酮甙 0 .80 4g·L-1,银杏内酯0 .0 6g·L-1)明显缩短心室肌细胞动作电位时程(APD) ,1 80 0稀释液致APD90 缩短 13% (P <0 .0 5 ) ,1 2 0 0稀释液致APD90 缩短 2 3% (P <0 .0 5 ) ;银杏叶提取物对心肌细胞L 型钙离子通道的开放有抑制作用 ,在 1 80 0时ICa L 峰值降低 15 % (P <0 .0 5 ) ,1 2 0 0时ICa L峰值降低 4 2 % (P <0 .0 5 ) ,均呈浓度依赖性 ,随着药物浓度的增加 ,I V关系曲线逐渐上移 ,但出现电流峰值的电压不变。结论 :银杏叶提取物能明显缩短APD ,抑制心肌细胞钙离子通道的开放 ,具有明显的浓度依赖关系 ,可能是其抗心律失常的分子基础。

AIM: To study the effects of Ginkgo biloba extract (EGB) on action potential (AP) and L type calcium channel in isolated guinea pig's ventricular myocytes. METHODS: AP was recorded by current clamp mode and I Ca L was recorded by voltage clamp mode using whole patch clamp technique. RESULTS: Action potential duration of repolarization 90%(APD 90 ) was shortened by 13%, 23% at the dilution of EGB 1800, and 1200, respectively(P< 0.05 ). L type calcium current (I Ca L ) was inhibited by EGB significantly in a concentration dependent manner. Peak I Ca L was reduced by 15% at the dilution of EGB 1800 and 42% at 1200, respectively(P< 0.05 ). I V relationship and the voltage of peak current did not change significantly. CONCLUSION: EGB can shorten APD and inhibit I Ca L in a concentration dependent manner, which may be one of critical basis on antiarrhythmia.