细胞外高K^+浓度对HCN(1,2)通道电生理特性的影响

Effect of high extracellular K^+ concentration on electrophysiological properties of HCN(1,2)

目的:研究细胞外高K+浓度对异源转染的中国仓鼠卵巢(CHO)细胞上的超极化激活的环核苷酸门控阳离子通道(HCN)1,2电生理特性的影响.方法:将HCN1,HCN2质粒DNA转染至CHO细胞,在两种不同细胞外K+浓度条件下用全细胞膜片钳记录细胞膜上HCN1,HCN2通道电流.结果:细胞外高K+浓度时,HCN1(pA/pF,112.30±21.50vs42.33±15.89;-140mV,n=6,P<0.05),HCN2(pA/pF,130.57±17.70vs26.98±4.62;-140mV,n=8,P<0.05)通道的电流密度增加,加快了HCN1(激活时间常数:ms,176.59±8.23vs306.12±45.66;-80mV,P<0.05),HCN2(激活时间常数:ms,385.24±31.58vs763.55±106.17;-80mV,P<0.05)通道的激活,减小了HCN2通道的半时最大激活电压[mv,-(110.05±1.73)vs-(126.09±2.85),P<0.05]和倾斜因子(11.70±0.46vs15.87±1.17,P<0.05),但对HCN1无影响.结论:细胞外高K+浓度对细胞膜上的HCN1和HCN2通道的电生理特性具有明显影响.

AIM： To evaluate the modulation of electrophysio- logical properties of HCN （1,2） by high extracellular K^＋ concen tration in heterologous transfected Chinese hamster ovarian （CHO） cells. METHODS： CHO cells were cotransfected with plasmid DNA encoding the cardiac HCN1 and HCN2. Whole-cell currents of HCN1 and HCN2 were recorded on the condition of two different extracellular K ＋ concentrations. RESULTS ： High extracellular K^＋ concentration significantly increased whole-cell current density of HCN1 （112.3 ±21.5 pA/pF, n =6 vs 42.3 ± 15.9 pA/pF, n =6; at - 140 mV, P 〈0. 05） and HCN2 （130.6±17.7 pA/pF, n=8 vs 27.0±4.6 pA/pF, n=8; at -140 mV, P〈0.05）. Moreover, high cxtracellular K＋ concentration accelerated the activation kinetic of HCN1 （tau 176.6 ± 8. 2 ms vs 306.1-＋ 45. 7 ms; at -80mV, P〈0.05） andHCN2 （tau385.2±31.6ms vs 763.6±106.2 ms; at -80 mV, P〈 0.05 ）. High extracellular K＋ concentration reduced the half maximal activation voltage （ - 110.1 ± 1.7 mV vs - 126.1 ± 2.9, P〈0.05） and the slop factor （11.7 ±0.5 mV vs 15.9±1.2 mV） of HCN2, but had no effect on HCN1. CONCLUSION： High extraeellular K^＋ concentration significantly affects the electrophysiological properties of HCN1 and HCN2 in CHO cells.