[Effect of cardiomyopeptidin for injection on energy metabolism in isolated hearts of young rats after ischemia-reperfusion injury].

Objective To investigate the effect of cardiomyopeptidin for injection on energy metabolism in isolated hearts of young rats after ischemia-reperfusion injury.Methods Fifty young healthy SD rats(aged 20±3 days and weighing 50-70 g)were randomly divided into 5 groups:a normal control group (NC group,n=10 ):the isolated hearts were stable for 20 min,and then 150 min continuous perfusion;a normal + cardiomyopeptidin group (NCMP group,n=10):the same as the normal control group,but K-H buffer solution was added with 50 mg/L cardiomyopeptidin,and 3 ischemia-reperfusion injury model groups,including a model control group (n=10):the isolated rat hearts were perfused with K-H buffer and then arrested with cardioplegic solution;a CMP1 group (n=10):the ST.Thomas’II cardioplegic solution was added with 100 mg/L cardiomyopeptidin;CMP2 group (n=10):K-H buffer and ST.Thomas’II cardioplegic solution was added with 50 mg/L and 100 mg/L cardiomyopeptidin respectively.The cardiac functional indexes were monitored,including heart rate,myocardial contractility and diastolic function,peak systolic and diastole myocardial velocities and coronary flow.In the 3 ischemia-reperfusion injury model groups,myocardial ultrastructure was observed through transmission electron microscopy;the creatine kinase isoenzyme (CK-MB) concentration was measured in the fluid outflow of coronary;the content of Na+-K+ ATPase,Ca2+-Mg2+ ATPase,total ATPase,superoxide dismutase (SOD),malondialdehyde (MDA),nitric oxide(NO),total nitric oxide synthase (TNOS),inducible nitric oxide synthase (iNOS) and aldosereductase were measured in the myocardium tissue;the relative expression levels of iNOS,eNOS,and Akr1b4 mRNA in the myocardial tissue were also detected by real-time fluorescence quantitative PCR.Results In the NC group,after prolonged perfusion,the cardiac function of isolated hearts had no significant change.Cardiomyopeptidin for injection had no significant effect on normal isolated hearts.Compared with the model control group,the cardiac function indexes and coronary flow in the groups treated with cardiomyopeptidin decreased much less.Cardiac myofibrillar fragmentation and mitochondrial swelling were observed in the control group,while in the CMP groups,the myocardial structure was nearly complete,and only mild mitochondria swelling and degeneration could be seen.After the reperfusion,the content of CK-MB was increased in the control group.Compared with the model control group,the CK-MB content was lower in the CMP1 and CMP2 groups.There was a slight decline in the contents of Na+-K+ ATPase,Ca2+-Mg2+ ATPase,and Total ATPase in the CMP1 and CMP2 groups,and an increase in SOD activity (P0.01 or P0.05).The concentration of NO and MDA produced after the ischemia-reperfusion injury was much lower in the CMP1 and CMP2 groups.The activity of iNOS and aldosereductase was inhibited,the expression levels of iNOS,and Akr1b4 mRNA were significantly down-regulated in the CMP1 and CMP2 groups.These changes were more prominent in the CMP2 group (P0.01 or P0.05).The eNOS mRNA levels in the CMP2 group was up-regulated (P0.05).Conclusion Cardiomyopeptidin for injection may improve the energy metabolism,improve coronary blood flow and car-diac function after the reperfusion,thus protecting immature myocardial against ischemia-reperfusion injury in young rats.Administration of it in both K-H buffer and ST.Thomas’II cardioplegic solution is better than adding it in cardioplegic solution alone.The mechanism may be associated with the inhibition the mRNA expression of iNOS and Akr1b4 in cardiomyocytes,the inhibition activity of iNOS and aldosereductase,and the decrease of NO production.