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

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(I_Ca-L)。结果:银杏叶提取物(原液含银杏黄酮甙0.804 g·L^-1, 银杏内酯0.06 g·L^-1)明显缩短心室肌细胞动作电位时程(APD), 1 ∶800 稀释液致APD₉₀ 缩短13 %(P <0.05), 1 ∶200 稀释液致APD₉₀缩短23 %(P <0.05);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 ∶800 时I_Ca-L 峰值降低15 %(P <0.05), 1 ∶200 时I_Ca-L 峰值降低42 %(P <0.05), 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。

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

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 %(APD₉₀)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.