Effects of enalapril postconditioning on myocardial injury induced by hind limb ischemia-reperfusion in rats

Objective To evaluate the effects of postconditioning with enalapril on myocardial injury induced by hind limb ischemia-reperfusion (I/R) in rats.Methods Thirty-six healthy male Sprague-Dawley rats,weighing 200-250 g,were randomly divided into 3 groups (n =12 each):group sham operation (group S),group I/R and group enalapril postconditioning (group EP).Limb ischemia was induced by occlusion of bilateral hind limbs for 3 h followed by 3 h reperfusion in groups I/R and EP.At 30 min before reperfusion,enalapril 0.04 mg/kg was injected via the internal jugular vein in group EP,while the equal volume of normal saline was injected in groups S and I/R.The rats were sacrificed at 3 h of repeffusion and myocardial specimens were obtained for microscopic examination of pathologic changes and for determination of cell apoptosis,Bcl-2 and Bax protein expression,superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in myocardial tissues.Apoptosis index was calculated.Results Compared with group S,apoptosis index and MDA content were significantly increased,Bax protein expression was up-regulated,Bcl-2 protein expression was down-regulated,and SOD activity was decreased in groups I/R and EP (P ＜ 0.05).Compared with group I/R,apoptosis index and MDA content were significantly decreased,Bax protein expression was down-regulated,Bcl-2 protein expression was up-regulated,and SOD activity was increased in group EP (P ＜ 0.05).The pathologic changes were significantly attenuated in group EP as compared with group I/R.Conclusion Enalapril postconditioning can attenuate myocardial injury induced by hind limb I/R in rats,and the mechanism may be related to reduction of apoptosis in cardiomyocytes and lipid peroxidation. Key words: Enalapril;  Reperfusion injury ;  Extremities ;  Myocardium