普罗帕酮对HERG钾通道孔胞膜外侧氨基酸突变前后的作用.doc

普罗帕酮对HERG钾通道孔胞膜外侧氨基酸突变前后的作用 作者：李绪勇　李晓艳　蒋学俊　唐艳红　王晞 作者单位：武汉大学人民医院心血管内科，湖北 武汉 430060 　　【摘要】 目的：探讨普罗帕酮对人类etheragogo相关基因（HERG）钾通道孔道胞膜外侧突变后结合能力的影响。方法： 将HERG野生型通道（WT）和HERG突变型通道（MT）的互补核糖核酸（cRNA）注射到非洲爪蟾卵母细胞，孵育24～72h后以不同刺激程序用双微电极法记录通道电流的表达。用Clampfit 9.2版本软件对数据进行分析。部分电流用相应的方程拟合。结果：HERG WT外侧的第628位点的甘氨酸突变为半胱氨酸（G628C）和第631位点的丝氨酸突变为半胱氨酸（S631C）成HERG MT后普罗帕酮与HERG MT通道的结合能力减小，50%抑制浓度（IC50）对HERG WT，HERG MT分别为5.31Μmol/L和7.81Μmol/L。普罗帕酮对HERG WT和HERG MT的阻滞效应都呈电压和浓度依赖性。普罗帕酮减小HERG WT，但未减少HERG MT通道的半数激活电压。结论：普罗帕酮是HERG通道的开放通道阻滞剂，HERG通道孔道膜外侧突变（G628C和S631C）能改变普罗帕酮与通道之间的结合能力，从而影响通道的激活。 　　【关键词】 普罗帕酮；突变；钾通道阻滞剂；心电图描记术 　　Effect of propafenone on HERG channel before and after the mutation near the extracellular mouth of the poreLI Xuyong　LI Xiaoyan,JIANG Xuejun,TANG Yanhong,WANG XiDepartment of Cardiology,People′s　Hospital　of Wuhan　University　Wuhan　Hubei　430060,ChinaAbstract：Objective:To discuss the effect of propafenone on HERG WT and HERG MT channel which had mutation near the extracellular mouth of the pore.Methods:HERG WT and HERG WT cRNAs were injected in Xenopus laevis oocytes.After 24～72 hours incubation, currents were recorded by twomicroelectrode voltage clamp technique using different depolarizing protocols.The data were analyzed with Clampfit 9.2 software.Some current traces were fitted with corresponding equations.Results:The binding ability of propafenone on HERG MT channel decreased after G628C and S631C mutation.Propafenone′s IC50 were 5.31 mol/L and 7.81 mol/L in HERG WT,HERG MT respectively.Propafenone produce a voltage and concentrationdependent inhibition on both HERG WT and HERG MT channel.Propafenone reduced the midpoint of activation voltage of HERG WT channels but no reduced the midpoint of activation voltage of HERG MT channels.Conclusion:Propafenone is an open channel blocker of HERG.The binding affinity to this channel can be reduced by the mutation near the extracellular mouth of the pore(G628C and S631C). 　　Key words：Propafenone;Mut