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jia tu ji xing que xue zao qi xin shi ji xi bao kua mo dian wei de bian hua ji mi zou shen jing de bao hu zuo yong
Pages: 318-324
Year: Issue:  3
Journal: Acta Physiologica Sinica

Keyword:  floating glass microelectrodemyocardial transmembrane potentialacute myocardial ischemiavagal stimulation;
Abstract: This study was carried out on rabbit hearts. Floating glass microelectrodewas used to record the transmembrane potentials of cardiac ventricular fibers insitu. Resting potential (RP), action potential amplitude (APA) and maximumupstroke velocity of phase 0 (dv /dt)_(max) were decreased (P0.01) 1-5 min aftercoronary occlusion. The duration of action potential, especially the time requiredfor 30% and 50% of recovery (APD_(30), APD_(50)), was shortened, and the durationof the plateau was shortened even more markedly. These changes in potentials of the ventricular cells during acute ischemia wereabolished by vagal stimulation, RP, APA, and (dv /dt)_(max) were increased (P0. 01).Vagal stimulation lengthened APD_(30),APD_(50), and APD_(90) under condition of na-tural heart rate, it was suggested that the lengthening of the APD during vagalstimulation was due to the decrease in heart rate. These results suggested that recovery of the transmembrane potentials of theischemic ventricular cells during vagal stimulation was beneficial to impulse conduc-tion in the ventricular muscles and to lengthening of the effective refractory period,which might play an important role in prevention of ventricular arrhythmia in earlystage of acute ischemia.
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