兔左右心室心外膜下细胞瞬间外向钾电流的异质性

目的:研究兔左心室和右心室心外膜下(epi)细胞复极1期瞬间外向钾电流(Ito1)的异质性。方法:以酶解分离方法获得兔左、右心室epi细胞,应用膜片钳全细胞记录技术定量观察左、右心室epi细胞Ito1的电压依赖性和峰值密度。结果:左、右心室epi细胞的Ito1均呈明显的电压依赖性。在测试电压为0mV和+60mV时,左、右心室epi细胞峰值Ito1密度分别为1.57pA/pF、5.52pA/pF(左心室)和2.44pA/pF和8.99pA/pF(右心室),并且在+10mV至+60mV的测试电压范围内,右心室epi细胞峰值Ito1密度均显著高于左心室epi细胞(P<0.05或P<0.01)。结论:兔右心室epi细胞峰值Ito1密度显著高于左心室epi细胞,这种电异质性分布可能为Brugada综合征等疾病致恶性心律失常的重要离子基础之一。

Study of the heterogeneity of transient outward potassium current in repolarization phase 1 between the rabbit left and right ventricular epicardial cells

Objective: To explore the heterogeneity of transient outward potassium current(I_ to1) in repolarization phase 1 between rabbit left and right ventricular epicardial cells. Methods: Using whole cell patch-clamp technique, we quantitatively determined the ionic density of I_ to1 from the left and right ventricular epicardial cells. Results: The activating process of I_ to1 of rabbit left and right ventricular epicardial cells exhibited evident voltage-dependency. At 0.5 Hz, +60 mV depolarizing test potential, the peak I_ to1densities of rabbit left and right ventricular epicardial cells reached 5.52 pA/pF and 8.99 pA/pF,respectively. Furthermore, at depolarizing test potentials ranging from +10 mV to +60 mV, the peak I_ to1densities of rabbit right ventricular epicardial cells were significantly higher than that of left ventricular epicardial cells(P<0.01～0.05). Conclusion: The results indicate that the rabbit right ventricular epicardial cells possess potent I_ to1. The voltage-dependent I_ to1 as well as the “spike and dome”-like action potential configuration mediated by I_ to1 is one of the prominent electrophysiolgical charicteristcs of repolarization phase 1 of the rabbit right ventricular epicardial cells.