Antiarrhythmic action of chronic melatonin in female rats

Abstract

Introduction: Arrhythmias are complications during reperfusion of the ischemic myocardium. Acute melatonin is antiarrhythmic, but there is less information about females´ animals receiving chronic treatment. Objective: We aim to evaluate the electrophysiological effects of melatonin in female rats. Methodology: Wistar Kyoto rats (WKY), ten weeks old, received melatonin dissolved in water (3-5 mg/kg/day, MEL) during 15 days. After this period, we evaluated the electrocardiogram in isolated hearts undergoing a 10 minutes regional ischemia, followed by reperfusion of 10 minutes. All procedures were approved by local Institutional Animal Care and Use Committees (106/2017). Results: Melatonin treatment shortened PR and QRS intervals and prolonged the QT interval and QT corrected for heart rate. Melatonin chronic treatment prevented the incidence of ventricular fibrillation during reperfusion (WKY 6/9; WKY+MEL 1/10; P=0.0198 by Fisher´s exact test). Conclusion: Our results confirmed the cardioprotective effects of oral melatonin administration in female rats and showed electrocardiographic modifications compatible with increased conduction and delayed myocardial repolarization as possible antiarrhythmic mechanisms. Universidad Nacional de Cuyo, SIIP project 06-J505