正常大鼠心室肌细胞动作电位和瞬时外向钾离子流的特点

目的研究正常Spraque-Dawley大鼠外层、中层和内层心室肌细胞动作电位(AP)和瞬时外向钾离子流(Ito)的特点。方法采用酶消化法获得大鼠外层、中层和内层心室肌细胞,以全细胞膜片钳技术记录心室肌细胞AP和Ito。结果成功记录到大鼠心室肌细胞外、中和内层心肌细胞AP和Ito。外层至内层心室肌细胞动作电位时程(APD)逐渐延长(P<0.05)。在+70mV刺激时外层至内层心室肌细胞Ito电流密度逐渐减小,分别为59.50±15.99,29.15±5.53和12.29±3.62pA/pF(P<0.05)。三层心室肌细胞曲线半激活电压、半失活电压及失活后恢复时间均无差异(P>0.05)。结论大鼠三层心室肌细胞AP形态和Ito大小存在分层差别。

The characteristics of action-potential and transient outward potassium current from ventricular myocytes of normal Spraque-Dawley rat

Objective To investigate the characteristics of action potential(AP) and transient outward potassium current(Ito) from epicardial,mid-cardial and endocardial ventricular myocytes of normal Spraque-Dawley rat.Methods Epicardial,mid-cardial and endocardial ventricular myocytes were isolated by enzyme digestion.AP and Ito were recorded by whole cell patch clamp configuration.Results AP and Ito were successfully recorded by whole cell patch clamp configuration.AP durations(APD) were gradually prolonged from epicardial to endocardial ventricular myocytes(P<0.05).Ito current densities at +70 mV were gradually decreased from epicardial to endocardial ventricular myocytes.They were 59.50±15.99,29.15±5.53 and 12.29±3.62 pA/pF respectively in epicardial,mid-cardial and endocardial ventricular myocytes,which was also significantly changed(P<0.05).Half-activated voltage,half-inactivated voltage and recovery time from inactivation were of no differences(P>0.05).Conclusion There are regional differences in the distribution of AP and Ito in rat epicardial,mid-cardial and endocardial ventricular myocytes.