直流电击对豚鼠快、慢反应心肌细胞电生理特性的影响

EFFECTS OF DIRECT CURRENT SHOCK ON THE ELECTROPHYSIOLOGICAL PROPERTIES OF FAST AND SLOW RESPONSE MYOCARDIUM OF GUINEA PIG

在豚鼠正常心室肌、高钾去极化和肾上腺素诱导的慢反应心肌及窦房结标本上，观察了直流电击（ＤＣＳ）的影响。结果表明，ＤＣＳ后正常心室肌跨膜电位出现抑制性改变，且呈电击能量依从性；ＤＣＳ的膜效应不受心肌兴奋状态的影响；ＤＣＳ对高钾去极化的慢反应心肌的作用小于正常心室肌；ＤＣＳ可引起窦房结自律性短暂降低。

In order to explore the effects of direct current shock (DCS) on the electrophysiological properties of fast and slow response myocardium, the influences of DCS on the normal ventricular muscle,ventricular muscle depolarized by elevated potassium and induced by epinephrine,and sino-atrial node of guinea pig were determined.It was shown that, after DCS,APD50,APD90,RMP,APA,Vmax and S3 decreased, and S2increased in DCS energy-dependent manner in normal myocardium.The membrane effects of DCS existed regardless of the state of excitation of the myocardium.After DCS, the action potentials of ventricular muscle elicited by high potassium and epinephrine showed shortened APDs.And DCS induced transient decrease of autorhythmicity in sino-atrial node.The results suggest that the responses of fast and slow response myocardium to DCS are different,and S-A node possesses the property of relative tolerance to DCS.