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Effect of lysophosphatidylcholine on the pacemaker current I_(f) of sheep cardial purkinje fibers in ischemia-like condition

Hu Youmin, Zhang Zhao, Gao Rubiao, Xu Youqiu

Department of Physiology, Shanghai Second Medical University. Shanghai 200025, China

Abstract

By using two microelectrode voltage clamp technique, the effects of “ischemia” and lysophosphatidylcholine (LPC), a main toxic metaboli te in acute ischendic myocardium,on pacemaker current I_(f) were examined in sheep cardiac Puri nje fibers. Afer perfusion with ischemia-like solution for 15, 30 and 60 min, the amplitude of I_(f) current was decreased at all meInbrane potential levels between -60 mV～-120 mV (n=5, P<0.05), both the activation time and half activation time reaching a steady state value were prolongated (n=5, P<0.05), with a result of shifting activation curve of If to a more hperpolarizing level. In normal Tyrode s0lution, the amplitudes of I_(f) at all measured potential levels were decreased significantly by LPC 2×10~(-5) mol/L (n=10, P<0.05); the steady-state activation curve of I_(f) was shifted to a more hyperpolarizing level but the activation time and half activation time to a steady-state value were not changed.

Key words: Lysophosphatidycholine;Pacemaker current I_(f);Myocardial ischemia

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Citing This Article：

Hu Youmin, Zhang Zhao, Gao Rubiao, Xu Youqiu. Effect of lysophosphatidylcholine on the pacemaker current I_(f) of sheep cardial purkinje fibers in ischemia-like condition. Acta Physiol Sin 1997; 49 (5): (in Chinese with English abstract).