The protective effects on rat myocardial ischemia and reperfusion injury by post-treatment with morphine

Objective To determine the protective effects of reducing myocardial ischemia and reperfusion injury(MI/R) by morphine adimistered post injury in rats.Methods Thirty-two male Sprague-Dawley(SD) rats were used for in vivo model of ischemia/reperfusion injury.Anesthetized rats were randomly assigned to the following four groups.Sham group in which the chest was opened without ligating the left coronary artery;Ischemia/reperfusion(I/R) group in which the saline was applied 5 min before reperfusion;Morphine(MOR) group in which 0.3 mg/kg morphine was given intravenously 5 min before reperfusion;Ischemic preconditioning(IPC) group in which 5 min ischemia and 5 min reperfusion for three cycles were applied before the long time ischemia procedure was administered.The area of infarction in myocardium was determined by tissue staining with Evan's blue and TTC.The contents of AST,CK-MB and LDH in the serum taken 120 min after reperfusion were measured to determine the severity of the cardiac infarction.Results Compared with I/R group,the size of infarction and the concentrations of CK-MB,AST and LDH are significantly decreased(P0.05) in MOR and IPC groups.