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,HCNI(pA/pF,112.30±21.50 vs 42.33±15.89;-140 mV,n=6,P＜0.05),HCN2(pA/pF,130.57±17.70 vs 26.98±4.62;-140 mV,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±8.23 vs 306.12±45.66;-80 mV,P＜0.05).HCN2(激活时间常数:ms,385.24±31.58 vs 763.55±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±0.46 vs 15.87±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.
Effect of high extracellular K+concen tration on electrophysiological proper ties of HCN(1.2)
AIM: To evaluate the modulation of electrophysiological properties of HCN( 1,2) by high extracellular K+ concentration 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 extracellular K+ concentration accelerated the activation kinetic of HCN1 (tau 176. 6 ± 8.2 ms vs 306.1 ±45.7 ms; at -80 mV, P<0.05) and HCN2 (tau 385.2 ±31.6 ms 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 extracellular K + concentration significantly affects the electrophysiological properties of HCN1 and HCN2 in CHO cells.
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