α2-adrenergic stimulation is protective against ischemia-reperfusion-induced ventricular arrhythmias in vivo

John J. Cai, Donald A. Morgan, William G. Haynes, James B. Martins, Hon Chi Lee

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

We previously reported that α2-adrenergic receptor (α2-AR) stimulation in Purkinje fibers in vitro prolongs action potential duration and suppresses β-adrenergic-induced delayed afterdepolarizations and sustained triggered activities. We examined the effects of α2-AR stimulation on reperfusion-induced ventricular arrhythmias [ventricular tachycardia/ventricular fibrillation (VT/VF)] in vivo. Arterial blood pressure, heart rate, surface electrocardiogram, and renal sympathetic nerve activities were recorded simultaneously in Sprague-Dawley rats. The incidence of VT/VF was 87.5% for controls, 50% for the β-blocker group, 72% for the α1-blocker group, and 12.5% for the α1 + β-blockers group (unopposed α2-adrenergic activation). Direct α2-AR stimulation with UK-14304 also prevented VT/VF. These effects were reversed by the α2-adrenergic antagonist yohimbine. Increases in renal sympathetic nerve activity were associated with left anterior descending coronary artery ligation and reperfusion (33 ± 1.5 and 62 ± 1.7% over baseline, respectively) in controls. Similar patterns were observed among all experimental groups irrespective of the incidence of VT/VF on reperfusion. We conclude that α2-AR stimulation has a potent antiarrhythmic effect on ischemia-reperfusion-induced VT/VF in vivo and that this effect is not centrally mediated.

Original languageEnglish (US)
Pages (from-to)H2606-H2611
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume283
Issue number6 52-6
DOIs
StatePublished - Dec 1 2002

Keywords

  • Purkinje fibers
  • Sympathetic nerve activities
  • Ventricular fibrillation
  • Ventricular tachycardia

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Fingerprint Dive into the research topics of 'α<sub>2</sub>-adrenergic stimulation is protective against ischemia-reperfusion-induced ventricular arrhythmias in vivo'. Together they form a unique fingerprint.

  • Cite this