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Electrophysiological effects of hydrogen sulfide on pacemaker cells in sinoatrial nodes of rabbits

Xu Meng, Wu Yuming, Li Qian, Wang Xin, He Ruirong

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

Abstract

The cardiac electrophysiological effects of hydrogen sulfide (H_(2)S) were examined on pacemaker cells in sinoatrial (SA) nodes of rabbits using intracellular microelectrode technique. The results obtained were as follows: (1) The velocity of diastolic (phase 4) depolarization (VDD) and rate of pacemaker firing (RPF) in normal pacemaker cells in SA nodes were decreased by NaHS (H_(2)S donor) (50, 100, 200 #mu#mol/L) in a concentration-dependent manner; (2) ATP-sensitive K~(+) (K_(ATP)) channel blocker glybenclamide (Gli, 20 #mu#mol/L) blocked the effects of NaHS (100 #mu#mol/L) on pacemaker cells; (3) Pretreatment with CsCl (2 mmol), a blocker of pacemaker current (I_(f)), did not affect the effects of NaHS (100 #mu#mol/L) on SA node pacemaker cells; (4) DL-propargylglycine (PPG, 200 #mu#mol/L), an inhibitor of cystathionine #gamma#-lyase (CSE), did not affect parameters of action potentials in pacemaker cells in SA nodes. All these results suggest that H_(2)S exerts a negative chronotropic action on pacemaker cells in SA nodes of rabbits. These effects are likely due to an increase in potassium efflux through opening K_(ATP) channels; If is unlikely to play a major role in these effects. In our study, there was no evidence for the generation of endogenous H_(2)S by CSE in SA node pacemaker cells.

Key words: Electrophysiology;hydrogen sulfide;Action potential;Sinoatrial node

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Citing This Article：

Xu Meng, Wu Yuming, Li Qian, Wang Xin, He Ruirong. Electrophysiological effects of hydrogen sulfide on pacemaker cells in sinoatrial nodes of rabbits. Acta Physiol Sin 2008; 60 (2): 175-180 (in Chinese with English abstract).