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An electrophysiological study on the arntr verntricular arrhythmic effect of adenosine in the guinea pig

ZHAO Zheng Hang, ZANG Wei-Jin, Yu Xiaojiang, ZANG YiMin

Department of Pharmacology, School of Medicine, Xi'an jiaotong University, Xian 710061； Department of Physiology Fourth Military Medical University, Xi'an 710032

Abstract

Using whole-cell patch clamp technique this study investigated the effects of adenosine(Ado) on action potential，L-type calcium current(1二L)，delayed afterdepolarizations(DADS)，and transient inward current(1) induced by is op rote re nol(ISO) in guinea pig isolated single ventricular myocytes .The results showed:(1)Ado alone had no significant direct effects on action potential and IC,.Lin guinea pig ventricular myocytes at 20一100 umol/ L.However，Ado significant1y attenuated the prolongation of action potential duration(APD) and the increase of the peak amplitude of 1二L induced by SO .ISO(10 nmol/ L) markedly increased APDso and APD9o from 340士21 ms to 486士28 ms and from 361士17 ms to 501士29 ms，respectively(P(0. 01)，and increased the amplitude of 1二L from一6. 53士1.4 pA/ pF to一18. 28士2.4 pA/pF(P(0. 01).The peak potential of current-potential relationship shifted to the left .Ado(50 umol/ L) abbreviated APDso，APD9o to 403士19 ms and 419士26 ms(P(0.01)，and decreased the peak amplitude of 1二Lto一10. 2士1.5pA/ pF(P(0. 01 VS ISO)，but did not change resting membrane potential(RMP)，action potential amplitude(AP A)，and overshoot(08).(2) ISO(30 nmol/ L) reproducibly elicited DADS with 100%incidence of DADS under this condition.Ado (50 umol/ L) completely inhibited ISO from inducing DADS.ISO(30 nmol/ L) elicited l,; with 2-second depolarizing voltageclamp pulses rising to+20 m V from a holding potential of一40 m V，the incidence of 1,; being 100%，and the 1,; was suppressed in the presence of Ado(50 umol/ L) with the incidence of l,; decreased to 14. 3%(P(0. 05).These data indicate that Ado antagonizes the stimulatory effect of ISO，and that the antiarrhythmic mechanism of Ado preventing Isoinduced DADS is due to the inhibition of intracellular Cat+overload through attenuating the prolongation of APD，the enhance of I_(Cal) and I_(ti).

Key words: Physiology;elect rophysiological study;pate卜clamp techniques;Adenosine;delayed afterdepolarization

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Citing This Article：

ZHAO Zheng Hang, ZANG Wei-Jin, Yu Xiaojiang, ZANG YiMin. An electrophysiological study on the arntr verntricular arrhythmic effect of adenosine in the guinea pig. Acta Physiol Sin 2003; 55 (1): (in Chinese with English abstract).