酮色林对人类ether-a-go-go相关基因钾通道的阻断作用(英文)  

Blockade of the human ether-a-go-go-related gene potassium channel by ketanserin

作　　者：涂丹娜[1] 邹安若[1] 廖玉华[1] 杜以梅[1] 王宪沛[1] 李璐[1] 

机构地区：[1]华中科技大学同济医学院附属协和医院心血管病研究所,心内科,离子通道病研究中心,武汉430022

出　　处：《生理学报》2008年第4期525-534,共10页Acta Physiologica Sinica

基　　金：the National Natural Science Foundation of China (No. 30470711)

摘　　要：采用双电极电压钳技术,研究酮色林对表达在非洲爪蟾卵母细胞上的野生型和Y652突变型人类ether-a-go-go相关基因(human ether-a-go-go-related gene,HERG)钾通道的阻断效应,观测HERG通道的分子位点特性改变对其阻断效应的影响。结果显示,酮色林以电压依赖性和浓度依赖性的方式阻断野生型的HERG钾通道电流。尾电流包裹程序记录电流显示酮色林对HERG钾通道微小的张力性阻断。阻断特征符合对开放状态通道的阻断特征。酮色林也能调节失活状态的HERG钾通道。位于孔道S6区的氨基酸位点突变Y652A和Y652R可显著减弱酮色林对HERG通道的阻断作用。同野生型HERG钾通道的阻断相比,Y652A突变使阻断的IC50提高72倍,而Y652R突变使阻断的IC50提高53倍。Y652A和Y652R的阻断效应之间没有明显的差别。以上结果提示,酮色林优先阻断开放状态的HERG钾通道,而Y652是酮色林与通道结合的关键位点之一。In the present study, we investigated the inhibitory action of ketanserin on wild-type （WT） and Y652 mutant human ethera-go-go-related gene （HERG） potassium channels expressed in Xenopus oocytes and the effects of changing the channel molecular determinants characteristics on the blockade with and without ketanserin intervention using standard two-microelectrode voltage-clamp techniques. Point mutations were introduced into HERG gene （Y652A and Y652R） and subcloned into the pSP64 plasmid expression vector. Complementary RNAs for injection into oocytes were prepared with SP6 Cap-Scribe after linearization of the expression construct with EcoR I. Clampfit 9.2 software was employed for data collection and analysis. Origin 6.0 software was used to fit the data, calculate time constants and plot histograms. The results showed that ketanserin blocked WT HERG currents in voltage- and concentration-dependent manner and showed minimal tonic blockade of HERG current evaluated by the envelope of tails test. The IC50 value was （0.38±0.04） μmol/L for WT HERG potassium channel. The peaks of the I-V relationship for HERG channel suggested a negative shift in the voltage-dependence of activation after using ketanserin, whose midpoint of activation values （V1/2） were （-16.59± 1.01） mV （control） vs （-20.59±0.87） mV （ketanserin） at 0.1 μmol/L, （-22.39±0.94） mV at 1 μmol/L, （-23.51±0.91） mV at 10 μmol/L, respectively （P〈0.05, n=6）. Characteristics of blockade were consistent with an open-state channel blockade, because the extent and rate of onset of blockade was voltage-dependent, increasing at more potentials even in the condition of leftward shift of activation curve. Meanwhile, in the different depolarization duration, the fractional blockade of end-pulse step current and peak tail current at 100 ms duration was significantly lower than that at 400 ms and 700 ms, which indicated that following the channel activation fractional blockade was enhanced by the activated chann

关 键 词：人类ether-a-go-go相关基因 钾通道 酮色林 电压钳技术 突变 

分 类 号：R96[医药卫生—药理学]