幼鼠和成年大鼠心室肌细胞起搏电流的改变

THE CHANGES OF FUNNY CURRENTS IN THE VENTRICULAR MYOCYTES OF NEONATAL RATS AND ADULT RATS

目的:运用膜片钳全细胞技术和实时定量聚合酶链式反应(PCR),探讨幼鼠和成年大鼠心室肌细胞起搏电流(If)及超极化激活的环核苷酸门控通道(HCN)亚型的改变。方法:分离3d的幼鼠和成年大鼠的心室肌细胞;测定HCN1、HCN2、HCN3和HCN4 mRNA的表达;记录If并研究其特性。结果:在新生大鼠心室肌细胞记录到If并得到电流密度-电压曲线,其激活电压约为-75mV;实时定量PCR检测HCN1、HCN2、HCN3和HCN4 mRNA在总HCN mRNA的表达中所占比例分别为0.23%±0.01%、83.58%±0.04%、0.79%±0.01%和15.44%±0.01%。在成年大鼠心室肌细胞也记录到超极化激活、并可以被4mmol/LCsCl阻断的If,其激活电压约为-115mV;HCN1、HCN2、HCN3和HCN4 mRNA在总HCN mRNA中所占比例分别为0.72%±0.02%、91.58%±0.08%、0.27%±0.02%和7.12%±0.02%。HCN2∶HCN4为(13.06±0.21)∶1。结论:随着年龄的增长,大鼠心室肌细胞HCN2所占比例增加;If值减小,激活电压变负。

Aim： To record funny currents （If）of ventricular myocytes and to analysize hyperpolarization-activated cation channel （HCN） expression in the rats of different ages. Methods： Fresh ventricular myocytes were isolated from 3 days rats and adult rats.HCN expressions were measured by real-time quantitative polymerase chain reaction （real-time PCR）. If was recorded through whole-cell patch clamp. Results： HCN1, HCN2, HCN3, HCN4 mRNA represented 0.23 %± 0.01%, 83.58 % ± 0.04 %, 0.79 % ± 0.01%, 15.44 % ± 0.01% of total HCN mRNA in the neonatal rats, respectively. If was recorded and the threshold for activation was -75 mV. In the adult rat, HCN1, HCN2, HCN3, HCN4 mRNA represented 0.72% ± 0.02%, 91.58% ± 0.08%, 0.27% ± 0.02 %, 7.12 % ±0.02 % of total HCN mRNA. The ratio of HCN2 to HCN4 was ≈ （ 13.06 ± 0.21） ： 1. The threshold for activation of If was ≈-115 mV in the adult rats. Conclusion. With the devdopment of rats, the value of If is smaller.The threshold for activation of If is more negative. The ratio of HCN2 to HCN4 is bigger.