Effects of U50488H on ventricular arrhythmias induced by myocardial ischemia and reperfusion in rats

    ZHANG Peng, ZHU Yunª²Long, WANG Yueª²Min, LI Mingª²Zhe, BI Hui, PEI Jianª²Ming

    Department of Physiology, School of Basic Medicine, Fourth Military Medical University, Xi¬ðan 710033, China

    ¡¾Abstract¡¿ AIM: To investigate the effects of U50488H (a selective §Üª²opioid receptor agonist) on ventricular arrhythmias induced by myocardial ischemia and reperfusion in rats. METHODS: Rats were randomly divided into four groups, i.e., control group, ischemia/reperfusion group (¢ñ/R), U50488H group and U50488H+¢ñ/R group respectively. Heart rate (HR), arterial blood pressure (ABP), left ventricular pressure (LVP), contractive function (+dp/dtmax) and diastolic function (-dp/dtmax) were examined in rats. The incidence of ventricular arrhythmias and arrhythmia score were also determined. RESULTS: ¢Ù HR, ABP, LVP and ¡Àdp/dtmax in rats decreased with the administration of U50488H; ¢Ú intravenous injection of U50488H before ¢ñ/R lowered the incidence of ventricular arrhythmias and arrhythmia score (P<0.05). The effect of U50488H was abolished in the presence of Norª²BNI, a selective ¦Êª²opioid receptor antagonist. CONCLUSION: ¦Êª²opioid receptor stimulation by U50488H alters the cardiac rhythm and reduces the occurrence of ventricular arrhythmia induced by myocardial ischemia and reperfusion. ......