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Effects of endothelin on the electrical activity of sino-atrial pacemaker cells of rabbit

Zhang Zhao, Li Yulong, He Ruirong

Department of Physiology, Institute of Basic Medicine, Hebei Medical University. Shijiazhuang 050017, Hebei

Abstract

The effects of endothelin-1 (ET-1) on the electrophysiological activity of pacemaker cells of rabbit sino-atrial node were examined by using intracellular microelectrode technique. The results obtained were as follows: (1) With superfusion of ET-1 (1-30 nmol/L), the velocity of diastolic depolarization (VDD) of pacemaker cells was significantly decreased in a concentration dependent manner, resulting in a reduced rate of pacemaker firing (RPF). (2) The decreases in RPF and VDD induced by ET-1 could be virtually blocked by pretreatment with ET_(A) receptor blocker BQ-123(20 or 100#mu#g/L). It was strongly suggested that the electrophysiological effects of ET-1 on the pace maker cells were mediated by the ET_(A) receptor. (3) The negative chronotropic action of ET-1 on the pacemaker cells was totally abolished by pretreatment with a kind of K_(ATP) channel blocker glibenclamide(10 #mu#mol/L).

Key words: Endothelin;Endothelin receptor;Sino-atrial node;Glibenclamide;BQ-123;Electrophysiology

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Citing This Article：

Zhang Zhao, Li Yulong, He Ruirong. Effects of endothelin on the electrical activity of sino-atrial pacemaker cells of rabbit. Acta Physiol Sin 1996; 48 (1): (in Chinese with English abstract).