乙醇对豚鼠心室肌细胞钙钠离子通道电流的影响

目的：观察乙醇对豚鼠心室肌细胞L-型钙离子通道电流（IGLL）和电压依赖性钠离子通道电流（INa）的影响，并探讨两者在乙醇致心肌损伤中的意义。方法：采用蛋白酶消化的成年豚鼠单个心室肌细胞及膜片钳全细胞技术，记录不同浓度乙醇对ICal.和INa的作用。结果：（1）乙醇抑制ICaL峰值，24mmol/L和240mmol/L乙醇抑制率差异有统计学意义（P〈0．05）。（2）24、80、240mmol／L乙醇使ICaL的电流-电压（I-V）曲线上移，在各测试电压下，电流均减小，但不影响曲线形状，用乙醇后最大激活电压仍在0mV左右。（3）24mmol／L乙醇基本不影响I、峰值，80、240mm01]L乙醇抑制I。峰值，与24mmol／L乙醇的抑制率差异有统计学意义（P〈0．05）。（4）24mmol／L乙醇对INa的I-V曲线无明显影响。80、240mmol／L乙醇使INa的I-V曲线上移，在各测试电压下，电流均减小，曲线形状无明显改变，用药后最大激活电压仍在-30mV左右。结论：致毒浓度（24mmol／L）的乙醇对ICal.具有明显抑制作用，可导致心肌产生负性肌力作用，动作电位时程缩短，诱发心律失常。但致毒浓度（24mmol／L）的乙醇不影响INa，而致死浓度（80mmol／L）对INa有明显抑制作用。

Effects of Ethanol on Calcium/sodium Channel Current in Guinea Pig Ventricular Myocytes

Objective:To study the effects of ethanol at different concentrations on L-type calcium channel current(ICa,L) and voltage-dependent sodium channel current(INa) in guinea pig ventricular myocytes,and to explore the significance in ethanol-induced cardiomyocyte injury.Methods:Using whole-cell patch-clamp technique in isolated guinea pig ventricular myocytes with an enzymatic procedure,ICa,L and INa were recorded before and after application of different concentrations of ethanol respectively.Results:The concentrations of ethanol,both 24 mmol/L and 240 mmol/L reduced the peak current of ICa,L.The percentage inhibitions for both concentrations of ethanol were significantly different(P < 0.05) .The concentration of ethanol,24,80 and 240 mmol/L shifted the I-V curve of ICa,L upwardly.The contour of I-V curve kept unchanged,and the peak current induced voltage remained 0 mV.The concentration of ethanol 24 mmol/L did not affect the peak current of INa.Ethanol of 80 and 240 mmol/L inhibited the peak current of INa.The percentage inhibition was significantly different compared with that of 24 mmol/L(P < 0.05) .Ethanol of 24 mmol/L did not affect the I-V curve of INa.The concentration of ethanol 80 and 240 mmol/L shifted the I-V curve of INa upwardly.The contour of I-V curve kept unchanged,and the peak current stimulating voltage remained-30 mV.Conclusion:The toxic concentration of ethanol(24 mmol/L) significantly inhibited ICa,L and contributed to a negative inotropic effect,decrease in action potential duration and development of arrhythmias.The toxic concentration of ethanol(24 mmol/L) did not affect INa,but the lethal concentration of ethanol(80 mmol/L) significantly inhibited it.