mHCN2和mHCN4基因在乳鼠心室肌中的表达及其起搏电流的特性

The gene expressions of mHCN2 and mHCN4 and the features of pacemaker current in neonatal rat ventricular myocytes

目的分析乳鼠心室肌mHCN2和mHCN4基因的表达及其起搏电流的特性。方法通过酶消化法分离乳鼠心室肌细胞,用全细胞膜片钳技术记录If电流并研究其特性;采用SYBR-GreenI染料进行实时定量PCR,测定乳鼠心室肌起搏基因mHCN2和mHCN4的表达。结果全细胞膜片钳记录到心室肌细胞If电流,得到电流密度-电压曲线,其激活电压约为-75mV;实时定量PCR检测mHCN2∶mHCN4为(5.56±1.35)∶1。结论乳鼠心室肌细胞有超极化激活、可被Cs+阻断的If电流;其基因表达以mHCN2为主。

Objective To analysize the features of pacemaker current and gene （hyperpolarization-activated cation channel, HCN） expression. Methods Fresh ventricular myocytes were enzymatically isolated from 1 to 3 days old rats. The funny current （If） was recorded and analyzed through whole-cell patch clamp. The expression of If gene （mHCN2 and mHCN4） in the neonatal rat ventricular myocytes was measured by real time PCR using SYBR Green PCR kit. Results Whole-cell patch clamp recorded Ⅰf and got current density-voltage curves. The threshold for activation of Ⅰf was -75 mV. The ratio of mHCN2 to mHCN4 was（5.56±1.35） ： 1. Conclusion Ⅰfof neonatal rat ventricular myocytes is activated by hyperpolarizing potentialand and blocked by 4 mM Cs^＋. MHCN2 represents a large amount of total HCN rnRNA.