模拟缺血对左心室中层心肌细胞钠电流和瞬间外向钾电流的影响

Effects of Simulated Ischemia on the Sodium Currents and Transient Outside Potassium Currents of Midmyo-cardial Cells from Rabbit Left Ventricle

目的研究模拟缺血对左心室中层心肌(M)细胞钠电流(INa)和瞬间外向钾电流(Ito)的影响。方法采用全细胞膜片钳记录技术直接记录左心室M细胞的INa和Ito,并观察模拟缺血10、20和30 min后M细胞INa和Ito的变化。结果模拟缺血后,左心室M细胞的INa电流密度-电压(Ⅰ-Ⅴ)关系曲线呈时间依赖性下移,INa稳态失活曲线呈时间依赖性左移,失活后再恢复无明显变化;心室M细胞的Ito Ⅰ-Ⅴ关系曲线上移,但随着缺血时间延长,上移Ⅰ-Ⅴ的关系曲线又逐渐下移,Ito稳态失活曲线和失活后再恢复曲线无明显变化。结论模拟缺血后左心室M细胞INa和Ito发生明显变化,可能是缺血相关的心律失常发生的离子流机制之一。

Objective To study the effects of simulated ischemia on the sodium currents (INa) and transient outside potassium currents (Ito) of midmyocardial (M) cells from the free wall of rabbit left .ventricle. Methods Single midmyocardial cells were isolated enzymatically from the free wall of rabbit left ventricle, INa and Ito were recorded by using patch clamp techniques in the whole cell configuration. Then simulated ischemia was given to the myocytes and INa and Ito were recorded again. Results The INa current density-voltage (Ⅰ-Ⅴ) relationship curves of the M cells decreased significantly after simulated ischemia, The INa inactivation curves shifted in the hyperpolarization direction, there were no significant differences in the INa recovery curves from inactivation. The Ito Ⅰ-Ⅴ curves of the M cells increased firstly and then decreased, there were no significant differences in the Ito inactivation curves and Ito recovery curves from inactivation. Conclusion INa and Ito of M cells are changed significantly after simulated ischemia, which may be one of the possible mechanisms of ventricular arrhythmias related to myocardial ischemia.