Electrophysiological Effects of Dexmedetomidine on Sinoatrial Nodes of Rabbits

• Published in: Acta Cardiologica Sinica Vol. 31; no. 6; pp. 543 - 549
• Main Authors: Pan, Xia, Zhang, Zhen, Huang, Ya-Yi, Zhao, Jing, Wang, Long
• Format: Journal Article
• Language: English; Chinese
• Published: 台灣 中華民國心臟學會 01.11.2015; Taiwan Society of Cardiology
• Subjects: Action potential; Cardiology; Dexmedetomidine; EPS and Arrhythmia; MEDLINE; Original; Pacemaker activity; SCI; Scopus; Sinoatrial node; Action potential; Pacemaker activity; Cardiology; Sinoatrial node; Dexmedetomidine
• ISSN: 1011-6842
• DOI: 10.6515/ACS20150424C

Background: The purpose of this study was to investigate the electrophysiological effects of dexmedetomidine on pacemaker cells in sinoatrial nodes of rabbits. Methods: Healthy rabbitswere anesthetized intravenously with sodium pentobarbital, and the heartswere quickly dissected andmounted in a tissue bath. Machine-pulled glass capillary microelectrodes whichwere connected to a high input impedance amplifier and impaled in dominant pacemaker cells. Thereafter, an intracellular microelectrode technique was used to record action potential. Results: The amplitude of action potential, velocity of diastolic (phase 4) depolarization, and rate of pacemaker firing in normal pacemaker cells in sinoatrial nodewere decreased by use of dexmedetomidine (0.5 ng/ml, 5 ng/ml, 50 ng/ml) in a concentration-dependent manner. Pretreatment with yohimbine (1 M), did not alter the effects of dexmedetomidine (5 ng/ml) on sinoatrial node pacemaker cells. Pretreatment with CsCl (2 mmol/L), dexmedetomidine (5 ng/ml) decreased the amplitude of action potential, but had no significant effect on other parameters of action potential. Conclusions: Dexmedetomidine exerts inhibitory electrophysiological effects on pacemaker cells in sinoatrial nodes of rabbits in a concentration-dependent manner, which may not be mediated by alpha 2- adrenoreceptor.