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Effects of platelet activating factor on action potentials and potassium channels in guinea-pig ventricular myocytes

Du Yimei, Tang Ming, Liu Changjin, Ke Qinmei, Luo Hongyan, Hu Xinwu

Department of Physiology, Tongji Medical College of Huazhong University of Science and Technology. Wuhan 430030, China；Department of Geriatrics, the Union Hospital, Tongji Medical College, Huazhong University of Science and Technology. Wuhan 430022, China

Abstract

This study was designed to investigate the effects of platelet activating factor (PAF) on the action potential and potassium currents in guinea-pig ventricular myocytes. Whole cell patch clamp techniques were used. With 5 mmol/LATP in the pipette electrode (mimic normal condition), 1 #mu#mol/LPAF increased APD_(90) from 225.8±23.3 to 352.8±29.8 ms (n=5, P＜0.05), decreased I_(K1) and I_(K) tail currents from -6.1±1.3 to -5.6±1.1 nA (n=5, P＜0.05) at -120 mV and from 173.5±16.7 to 152.1±11.5 pA (P＜0.05, n=4) at +30 mV,respectively. But PAF had no effect on I_(K1) at potentials within the normal range of membrane potentials (between -90 mV and +20 mV).restore prolongation of APD induced by PAF. In conclusion, in guinea-pig ventricular myocytes, with 5 mmol/L ATP in the pipette PAF hence a decrease in APD. It is suggested that PAF may amplify the heterogeneity between ischemic and normal cardiac myocytes during ischemia/reperfusion, which may play a vital role in the pathogenesis of the arrhythmias induced by ischemia/reperfusion.

Key words: Platelet activating factor;Cardiac myocyte;Action potential;Potassium channels;Patch clamp technique

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Citing This Article：

Du Yimei, Tang Ming, Liu Changjin, Ke Qinmei, Luo Hongyan, Hu Xinwu. Effects of platelet activating factor on action potentials and potassium channels in guinea-pig ventricular myocytes. Acta Physiol Sin 2004; 56 (3): (in Chinese with English abstract).