中文摘要：

目的：观察咪达唑仑对人胚肾上皮细胞（HEK-293）中异源表达的人类相关基因（h ERG）钾电流作用及其机制。方法：利用全细胞膜片钳技术,观察咪达唑仑对h ERG钾通道的抑制作用,分析其对通道激活、失活动力学过程的影响以及咪达唑仑对Y652A和F656C突变型h ERG钾通道的作用。结果：咪达唑仑浓度依赖性地抑制h ERG钾电流,其IC50值为（1.31±0.32）μmol/L。1.0μmol/L的咪达唑仑加药前后半数激活电压V1/2由（2.32±0.38）m V变为（-1.96±0.83）m V;加药前后半数失活电压V1/2由（-49.25±0.69）m V变为（-57.53±0.53）m V（P〈0.05）,失活曲线左移;与野生型（WT）比较,Y652A和F656C突变型可显著减弱咪达唑仑对h ERG通道的阻断作用。结论：咪达唑仑能阻断h ERG钾通道,失活速度加快,Y652和F656可能是咪达唑仑与h ERG钾通道结合的关键位点。

英文摘要：

Objective： To investigate the effect of midazolam on human ether-a-go-go （bERG） K ＋ channels exogenously expressed in hu- man embryonic kidney cells （HEK-293） and the underlying molecular mechanisms. Methods： Whole-ccll patch clamp technique was used to record WT, Y652A and F656C bERG K＋ curium expressed in HEK-293 cells. Results： Midazolam inhibited hERG K＋ current in a concen- tration-dependent manner, the half-maximum block concentrations （ IC50 ） values were （ 1.31 ±0.32） μmol/L. The half-activation voltage （V1/2） were （2.32 ± 0.38） mV for the control and （-1.96 ± 0.83） mY for 1.0 tmaol/L midazolam. The half-inactivation voltage （Vl/2） was slightly shifted towards negative voltages from （-49.25 ± 0.69） mV in control to （-57.53 ± 0.53） mV after 1.0 μmol/L midazolam （ P 〈 0.05）. Mutations in drug-binding sites （Y652A or F656C） of the bERG charmel significantly attenuated the bERG current blockade by mida- zolam. Conclusion： Midazolam can block hERG K ＋ channel and cause the speed of inactivation faster. Mutations in the drug-binding sites （Y652 or F656） of the bERG channel were found to attenuate hERG current blockage by midazolam,