Abstract:

Abstract:Objective
To observe the protective effect of adrenomedullin(ADM)  on the myocardial injury following limb ischemia reperfusion(LIR) in rats and its mechanism.Methods 30 Wistar rats were randomly divided into control group,LIR group and ADM+LIR group(n=10).The plasma and myocardial tissue concentrations of endothelin-1(ET-1) were determined by using radioimmunoassay.The levels of creatine kinase(CK),creatine kinase MB isoenzyme(CK-MB) in plasma and malondialdehyde(MDA),xanthine oxidate(XOD),superoxide dismutase(SOD) in myocardial tissue were measured in each group.The pathological changes in the myocardium were observed.Immunohistochemistry technique was used to determine the expression of ET-1 in myocardium.Results Compared with control group,the levels of ET-1,CK,CK-MB in plasma and ET-1,MDA,XOD  myocardial tissue were increased(P<0.01),and the content of SOD in LIR group was decreased (P<0.01).Compared with LIR group,the levels of ET-1,CK,CK-MB in plasma and ET-1,MDA,XOD of myocardial tissue in ADM+LIR group were decreased(P<0.05 or P<0.01),and the content of SOD was increased(P<0.05).The pathological results showed that the myocytes was irregular,the muscle fiber was dissolved,the myofilament was disorder,the marked vascular congestion was observed in LIR group.In ADM+LIR group,the myocardial injury was lightened.The immunohistochemical results showed that the expression of ET-1 was significantly decreased in ADM group compared with LIR group（P<0.01）.Conclusion ADM can protect the myocardium following LIR in rats and the protective effects may be related to anti-oxidation and inhibition of synthesis of  ET-1.

Key words: adrenomedullin;reperfusion injury;oxygen free radical;endothelin-1;myocardium