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Characterization of outward current in mouse ventricular myocytes

Zhou Jun, Hao Xuemei, Wang Zhongmin, Jin Manwen, Qian Jiaqing, Liu Taifeng

National Key Laboratory of Biomembrane and Membrane Bioengineering, College of Biosciences, Peking University. Beijing 100871； China

Abstract

During brief depotarizations to potentials positive to-50mV, outward K~(+) currents in these cells rise rapidly to a peak followed by a slower decay to an apparent plateau. The relative peak to plateau amplitudes in a single cell varied as a function of the holding potential (HP) from which the currents were evoked. Reversal potentials for the peak and plateau components were -64.3±3.9mV and -53.3±2.9mV, respectively(uncorrected for junction potentials). The outward current decay is well described by double exponential fits, whereas the time course of peak I_(out) decay following a 500 ms prepulse is best fitted by single exponential function, indicating the presence of two distinct components, I_(kf) and I_(ks), of the outward currents in mouse ventricular cells. Application of 4-AP were accompanied by a marked attenuation of peak I_(out) and plateau I_(out), indicating that both I_(kf) and I_(ks) display similar sensitivities to 4-AP.

Key words: Potassium channel;Electrophysiology;Heart;Mouse;Whole-cell patch-clamp technique

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Citing This Article：

Zhou Jun, Hao Xuemei, Wang Zhongmin, Jin Manwen, Qian Jiaqing, Liu Taifeng. Characterization of outward current in mouse ventricular myocytes. Acta Physiol Sin 1995; 47 (6): (in Chinese with English abstract).