人胚肾(HEK293)细胞自身的钾通道

Endogenous potassium channels in human embryonic kidney (HEK293) cells

目的研究人胚肾(HEK293)细胞自身的电压依赖性的钾通道。方法利用全细胞膜片钳技术,记录HEK293细胞上的外向电流及其通道的电生理特点。结果HEK293细胞上未发现氯电流。59.7%的细胞表达一种类似瞬间外向钾电流(Ito)的钾电流,该电流对4-AP敏感,2mmol/L的4-AP可明显抑制此电流。在40mV时,此电流幅度为(175±112)pA。失活曲线显示其通道的半数失活电压为(-3.5±0.9)mV,斜率为(6.3±0.8)mV。该通道从失活状态中恢复的时间常数为(333.3±33.9)ms,其失活动力学曲线呈钟形。结论HEK293细胞自身存在Ito样电流,且此电压依赖性钾通道是其自身表达的最主要的有功能的离子通道,提示在利用此广泛应用的表达系统来研究外源性离子通道的时候,应该加倍注意。

Objective To investigate the endogenous voltage-gated potassium channels in human embryonic kidney （HEK293） cells. Methods The standard whole-cell recording method was used to record different outward currents in HEK293 cells. And the detailed electrophysiology of these channels were studied. Results No obvious chloride currents were found in native HEK293 cells. No obvious background potassium currents or delayed rectifier potassium currents were recorded either. 4-aminopyridine （4-AP） sensitive potassium currents were found in 59.7% of HEK293 cells. 2 mmol/L 4-AP can completely inhibit this current. The amplitude of this current was （175±112）pA at 40mV. The inactivation curve shows the V1/2 was （-3.5±0.9） mV, with a slope of （6.3±0.8）mV. The inactivation kinetics of this channel was bell-shaped. The recovery time constant of this channel from inactivation was （333.3±33.9）ms. All these data suggest this current is similar to transient outward potassium current （Ito） and this channel is the main endogenous functional channel in HEK293 cells. Conclusion Transient outward potassium current exists in native HEK293 cells, which is a widely used expressing system of different protein including channel protein. So we should be cautious in explaining the results of the expressed channels in HEK293 ceils. A control should be necessary.