犬心室肌Iks通道的分布及Iso和chromanol 293B对其影响  

Distribution of the Iks channels in the canine ventricular myocardium and the effects of isoproterenol and chromanol 293B on them

作　　者：郭凯[1] 黄从新[1] 王腾[1] 赵庆彦[1] 刘文举[1] 刘捷[1] 

机构地区：[1]武汉大学人民医院心内科,430060

出　　处：《实用医学杂志》2006年第6期620-623,共4页The Journal of Practical Medicine

摘　　要：目的:探讨LQT1发病的分子生物学基础以及LQT1患者在交感神经兴奋时发生室性心律失常的电生理机制。方法:实验分别采用westernblot方法检测慢激活延迟整流性钾电流(Iks)通道在犬左心室肌中层和外层的分布情况,以及用玻璃微电极和特制的金属电极,同步记录犬楔形心室肌中层和外层心肌细胞的跨膜动作电位(TAP)和跨壁心电图(TECG),并观察chromanol293B(Iks阻断剂)和异丙肾上腺素(Iso)对心室肌细胞动作电位时程(APD90)、跨壁复极离散度(TDR)、QT间期的影响。结果:Iks通道在中层的分布明显少于外层(P<0.01),chromanol293B使中层和外层心室肌细胞APD90均匀延长(P<0.05),TDR增加不明显(P>0.05),TECG示QT间期延长(P<0.05)。加入Iso后,中层心室肌细胞APD90延长(P<0.05),并出现早期后除极(EAD),外层心室肌细胞APD90缩短(P<0.05),TDR明显增加(P<0.05),TECG示QT间期延长(P<0.05),并能自发产生室性早搏和室性心动过速。结论:Iks通道在心室肌中层和外层分布不均一,而chromanol293B和Iso对中层和外层Iks通道的影响也不一致,这可能是交感神经兴奋使LQT1患者发生室性心律失常的机制。Objective To explore the electrophysiologic mechanism of ventricular arrhythmia in response to sympathetic stimulation in the long QT syndrome （LQTS）. Methods Western blot was used to measure the concentration of the protein of the Iks channels in the middle and outer layer of the canine ventricular myocardium. The transmembrane action potentials （TAP） and a transmural electrocardiogram（TECG） in cells from a wedge middle and outer layer of canine left ventriclar myocardium were simultaneously recorded, and the effects of isoproterenol （Iso） and chromanol 293B on action potential duration （APD90）, transmural dispersion of repolarization （TDR） and QT interval were examined. Results The densities distribution of Iks channels were much higher in the outer layer of myocardium than in the middle layer（ P 〈 0. 01 ）. Chromanol 293B evenly prolonged APD90 of the cells in the two layers （ P 〈 0.05） and QT interval （ P 〈 0.05） without markedly increasing TDR（ P 〉 0. 05）, But chromanol 293B plus Iso could prolong APD90 of cells in the middle layer （ P 〈 0. 05） and induceearly after depolarization （EAD）, while abbreviate APD90 of cells in the outer layer （ P 〈 0. 05）, and significantly increase TDR and QT interval（ P 〈 0. 05）. Spontaneous ventficular tachycardia （VT） could be induced in the administration of Iso. Conclusions The distribution of Iks channels in the middle and outer layer of myocardium is uneven. Iso and chromanol 293B have different effects on the action potentials of the cells in the middle and outer layer of myocardium. These may be involved in the occurrence of ventricular arrhythmia due to sympathetic stimulation in LQTI.

关 键 词：QT延长综合征 心室肌 Iks通道 跨膜动作电位 跨壁心电图 

分 类 号：R33[医药卫生—人体生理学]