心肌梗死1周后梗死边缘区心室肌细胞快钠通道电流跨壁异质性的变化

Transmural heterogeneity changes of sodium current in cardiac myocytes of infarction border zone one week after myocardial infarction

目的探讨心肌梗死1周后梗死边缘区心肌细胞快钠通道电流（INa）跨壁异质性的变化。方法30只兔随机分为3组，其中两组结扎家兔左前降支建立心肌梗死动物模型，分别为心肌梗死组和假手术对照组，另一组为正常对照组。1周后，用膜片钳技术研究左心室梗死边缘区三层心肌细胞INa的改变。结果正常对照组左室三层细胞的钠电流存在异质性，M细胞的峰值INa是心内膜和心外膜细胞的2倍多；M细胞的INa失活最快；对照组与假手术组无明显差别。心肌梗死组三层细胞的INa I—V曲线均上移，以M细胞变化最显著，INa稳态失活曲线均左移，以心外膜细胞变化最显著。结论左室心肌细胞的INa存在跨壁异质性；心肌梗死对INa的跨壁异质性有明显影响。

Objective To investigate the transmural heterogeneity changes of sodium current （INa） in cardiac myocytes of infarction border zone one week after myocardial infarction. Methods The rabbits （ n = 30） were randomly divided into 3 groups, among them 2 groups （the myocardial infarction group and sham-operation group） were given the ligature of left anterior coronary artery for establishing the model of myocardial infarction, and another group was taken as normal control group. After one week the changes of INa in three subtypes of cardiac myocytes in the infarction border zone of left ventricle were studied by applying patch clamp technique. Results In the normal control group INa in three subtypes of cardiac myocytes showed heterogeneity. INa peak value of myocardiac M cells （M cells） was two times higher than that of endomyocardial cells or epicardial cells. The deactivation of IRa M cells was the fastest. There was no significant different between the normal control group and sham-operation group. In the myocardial infarction group INa current-voltage curve （I-V） of three subtypes of cardiac myocytes moved up and most significant in M cells. INa steady-state deactivation curve of three subtypes of cardiac myocytes shifted to the left and most sig- nificant in the epicardial cells. Conclusion There is transmural heterogeneity in INa of cardiac myocytes of left ventricle. Myocardial infarction has significant effect on INa transmural heterogeneity.