Effect Of Preconditioning With Isoproterenol On Myocardial Ischemia/Reperfusion Injury

Objective:To investigate the effect of preconditioning with isoproterenol(ISO)on myocardial ischemia/reperfusion(I/R)injury in rats and elaborate the possible mechanism.Methods:32 male SD rats were divided into sham group,I/R injury group,ISO group,and selective ?2-adrenergic recepter(?2-AR)antagonist ICI118551+ISO-I/R group(ICI group)based on random number table(8 in each group).Myocardial HE staining was used to observe cardiomyocyte morphology,Western blot analysis was used to detect the expression level of phosphorylated serine/threonine kinase(P-Akt),cardiomyocytes apoptosis rate was analyzed with in situ end labeling,caspase-3 relating with cardiomyocytes apoptosis was measured by immunohistochemical technique,xanthine oxidase method was used to examine SOD activity,and the concentration of MDA was measured by thiobarbituric acid method.Results:In comparison with the I/R group,the degree of myocardial injury was remarkably reduced,the expression of P-Akt was increased,cardiomyocytes apoptosis rate was lower,the expression of caspase-3 was downregulated,SOD activity was augmented and MDA concentration was decreased significantly(P<0.05)in ISO group.While compared with ISO group,the level of myocardial injury was remarkably increased,the expression of P-Akt was decreased,cardiomyocytes apoptosis rate was increased,the expression of caspase-3 was augmented,SOD activity was decreased and MDA concentration was increased remarkably(P<0.05)in ICI group.Conclusion:ISO preconditioning plays a protective role in rat myocardial I/R injury possibly through activating ?2-AR and stimulating PI3K-Akt signaling pathway.