家兔右室流出道细胞双孔钾通道电流特性的分析研究

Difference in Current Densities of Two Pore Domain Potassium Channel between Ventricular and Ventricular Outflow Tract Cardiomyocytes in Rabbit Heart

目的已知特发性室速主要起源于右室流出道(RVOT),由于技术上的困难,目前对特发性右室流出道室速(RVOT-VT)的离子通道机制研究很少,本实验意在探索右室心室肌(RV)和RVOT的双孔钾通道电流(IK2p)的特性及其在RVOT-VT发生机制中可能参与的作用。方法采用全细胞膜片钳技术记录右室和右室流出道心肌细胞的单细胞电流。结果 RVOT的稳态外向电流较右室的小。对稳态电流进一步研究发现,右室流出道和右室心肌细胞上均存在IK2p。右室流出道细胞的IK2p电流密度明显小于右室细胞。结论首次在电生理水平上,证实了家兔右室心肌细胞上存在IK2p,RVOT心肌细胞的IK2p电流密度小于RV心肌细胞,是构成右室流出道APD离散度增大及外向电流降低的基础,从而易出现EAD,进而促进RVOT-VT的发生。

Objective Idiopathic ventricular tachycardia mainly originates from right ventricular outflow tract（RVOT）.The ionic channel mechanism of idiopathic ventricular tachycardia arising from right ventricular outflow tract（RVOT-VT）has been seldom reported experimentally,for the technical difficulties.The aim of the experiment was to explore the difference of IK2p between the myocardial cells in RVOT and free right ventricular wall（RV）in rabbit heart and the mechanism of the ventricular tachycardia genesis from RVOT.Methods The ionic currents of rabbit cardiomyocytes in RVOT and in RV were recorded with the whole-cell patch-clamp technique.Results The steady-state current in RVOT cardiomyocytes was less than that in RV.The further observation on the steady-state current showed that IK2p currents existed in rabbit RVOT and RV myocardial cells,displaying that IK2p current in RVOT was less than that in RV.Conclusion It was the first time on the electrophysiological level verified the existence of the IK2p current in rabbit.The low IK2p current density in some RVOT myocytes led to lower the outward current and prolonged APD in RVOT myocytes.These might induce EAD and resulted to genesis of RVOT-VT.