Cardioprotective effect of Thymoquinone: A constituent of Nigella sativa L.,against myocardial ischemia/reperfusion injury and ventricular arrhythmias in anaesthetized rats

Reperfusion of the ischemic myocardium causes the myocardial injury and life-threatening ventricular arrhythmias in human. this study aimed to investigate the effects of thymoquinone (tq) on myocardial ischemia/reperfusion (i/r) injury and ischemia-and reperfusion-induced ventricular arrhythmias in anaesthetized rats. adult male wistar albino rats were divided into two groups,each containing a control and tq-treated subgroups. in group i,the myocardial infarct size was determined by triphenyl tetrazolium chloride staining following 2-h reperfusion preceded by 30 min of ischemia. in group ii,a 6-min myocardial ischemia was followed by a 10-min reperfusion. tqtreated subgroups were treated with tq (10 mg/100μl/kg,i.p.) and the control subgroups were treated with the vehicle (100 μl/kg,i.p.) 20 min prior to the ischemic period. ischemia was induced by ligating the left main coronary artery,followed by reperfusion. tq treatment reduced the infarct size (15±4% versus 69±6%,p<0.01). pretreatment with tq decreased arrhythmia scores,as well as the incidence of ventricular tachycardia and the incidence of ventricular fibrillation during the reperfusion period (arrhythmia scores: 1.4±0.3 versus 4.4±0.3,p<0.01). these results suggest that tq confers protection against myocardial i/r injury and suppresses reperfusion-induced arrhythmias.