Effects of dexmedetomidine preconditioning on ischemia-reperfusion injury to isolated rat hearts

Abstract

Objective To investigate the effects of dexmedetomidine preconditioning on ischemia-reperfusion(I/R) injury to isolated rat hearts.Methods Twenty-four male Wistar rats weighing 230-260 g were anesthetized with intraperitoneal 10％ chloral hydrate 400 mg/kg and heparin 500 IU/kg.Their hearts were excised and perfnsed in a Langendorff apparatus with K-H solution saturated with 95％O2-5％CO2 at 37 ℃.Twenty-four isolated rat hearts were randomly divided into 3 groups after 10 min of equilibration(n =8 each):group I/R,dexmedetomidine 0.23,2.30 ng/ml preconditioning group (groups D I,D Ⅱ ).In group I/R,the hearts were perfused continuously for another 30 min.In groups D Ⅰ and D Ⅱ,the hearts were perfused with K-H solution containing dexmedetomidine 0.23,2.30 ng/ml for 20 min followed by 10 min washout before ischemia.All hearts were subjected to 30 min of global ischemia followed by 120 min of reperfusion with K-H solution.The activities of creatine kinase(CK) and lactate dehydrogenase(LDH) in coronary effluent were measured at the end of 10 min equilibration(balance),and at 5,30,60 and 120 min of reperfusion.Myocardial tissues were obtained at the end of reperfusion for determination of the activity of SOD and the content of MDA.Results Compared with group I/R,the CK and LDH activities in coronary effluent and MDA content in myocardium were significantly decreased,the SOD activity was significantly increased in groups D I and D Ⅱ ( P ＜ 0.05).Compared with group D Ⅰ,the CK and LDH activities in coronary effluent and MDA content in myocardium were significantly decreased,the SOD activity was significantly in group DⅡ ( P ＜ 0.05).Conclusion Dexmedetomidine preconditioning can attenuate myocardial I/R injury in a concentration-dependent manner in rats. Key words: Dexmedetomidine; Myocardial reperfusion injury