High extracellular potassium ion concentration attenuates the blockade action of ketanserin on Kv1.3 channels expressed in xenopus oocytes  

作　　者：LIANG Zhen-tao WANG Xian-pei ZENG Qiu-tang LIAO Yu-hua ZOU An-ruo LI Lu TU Dan-na 

机构地区：[1]Department of Cardiology, Institute of Cardiovascular Diseases, Ion Channelopathy Research Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China [2]Department of Cardiology, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, China

出　　处：《Chinese Medical Journal》2008年第24期2584-2591,共8页中华医学杂志（英文版）

摘　　要：Background Ketanserin （KT）, a selective serotonin （5-HT） 2-receptor antagonist, reduces peripheral blood pressure by blocking the activation of peripheral 5-HT receptors. In this study electrophysiological method was used to investigate the effect of KT and potassium ion on Kv1.3 potassium channels and explore the role of blocker KT in the alteration of channel kinetics contributing to the potassium ion imbalances. Methods Kv1.3 channels were expressed in xenopus oocytes, and currents were measured using the two-microelectrode voltage-clamp technique. Results KCI made a left shift of activation and an inactivation curve of Kv1.3 current and accelerated the activation and inactivation time constant. High extracellular [K^＋] attenuated the blockade effect of KT on Kv1.3 channels. In the presence of KT and KCI the activation and inactivation time constants were not influenced significantly no matter what was administered first. KT did not significantly inhibit Kv1.3 current induced by tetraethylammonium （TEA）. Conclusions KT is a weak blocker of Kv1.3 channels at different concentrations of extracellular potassium and binds to the intracellular side of the channel pore. The inhibitor KT of ion channels is not fully effective in clinical use because of high [K^＋]. and other electrolyte disorders.Background Ketanserin （KT）, a selective serotonin （5-HT） 2-receptor antagonist, reduces peripheral blood pressure by blocking the activation of peripheral 5-HT receptors. In this study electrophysiological method was used to investigate the effect of KT and potassium ion on Kv1.3 potassium channels and explore the role of blocker KT in the alteration of channel kinetics contributing to the potassium ion imbalances. Methods Kv1.3 channels were expressed in xenopus oocytes, and currents were measured using the two-microelectrode voltage-clamp technique. Results KCI made a left shift of activation and an inactivation curve of Kv1.3 current and accelerated the activation and inactivation time constant. High extracellular [K^＋] attenuated the blockade effect of KT on Kv1.3 channels. In the presence of KT and KCI the activation and inactivation time constants were not influenced significantly no matter what was administered first. KT did not significantly inhibit Kv1.3 current induced by tetraethylammonium （TEA）. Conclusions KT is a weak blocker of Kv1.3 channels at different concentrations of extracellular potassium and binds to the intracellular side of the channel pore. The inhibitor KT of ion channels is not fully effective in clinical use because of high [K^＋]. and other electrolyte disorders.

关 键 词：KETANSERIN Kv1.3 potassium channel potassium ion IMMUNOMODULATION electrolytes imbalances channel kinetics 

分 类 号：R4[医药卫生—临床医学]