Protective Effects Of Delayed Ischemic Preconditioning On Ischemia/reperfusion Injury In The Coronary Endothelial Cells

Objective: To study the protective effects of delayed ischemic preconditioning on coronary endothelial function by ischemia/reperfusion, and investigate the changes of the content of nitric oxide(NO), malondialehyde(MDA) and superoxide dismutase(SOD) during the period of IR and IPC, then to analysis the expression of endothelial NO synthase (eNOS) and inducible NO synthase(iNOS) in coronary endothelial cells by immunohistochemistry.Methods: Eighteen rabbits were divided randomly into three groups: Control group (CON group, n=6); Ischemia/reperfusion group(IR group, n=6); Ischemic preconditioning group (IPC group, n=6). In I/R group and IPC group , blood samples were taken for analysis the change of the content of NO . MDA and SOD after opening bosom, before ischemia, 90 minutes after repurfusion. At the end of experiment, the rabbits of three groups were excised the hearts and sliced the left ventricles transversely into 5-10mm thick slices. Then sliced a little myocardium supplyed with LAD and embedded into paraffin to study the expression of eNOS and iNOS in endothelial cells by immunohistochemistry.Results: NO was found significantly increased before ischemia than after opening bosom in IPC group. Compared with after opening bosom, NO was also increasd in both two groups after reperfusion.Before ischemia, IPC group was higher than IR group and they have no significant difference after reperfusion(P>0.05). After reperfusion, the content of MDA was markedly increased in IR group comparing with before ischemia and after opening bosom, but in IPC group, before ischemia was lower than after opening bosom and there was no difference between after reperfusion and opening bosom(P>0.05). IPC group was both lower than IR group afterreperfusion and before ischemia. About the activity of SOD, IR group and IPC group were both not significant difference after opening bosom and before ischemia, furthermore, two groups had no distinction. After reperfusion, IR group was markedly decreased, but IPC group was significantly enhanced. There was no significant difference between IPC group and CON group about the expression of eNOS in endothelinal cells(P>0.05), but IPC group was higher than IR group. Three groups didn't find the expressiong of iNOS.Conclusion: Delayed IPC increases the release of NO and reduses the free radicals in the early phase and preserves appropriate level of NO and free radicals during reperfusion, meanwhile, IPC improves the activity of SOD and increases the expression of eNOS in coronary endothelial cells. NO produced by eNOS is important on the delayed IPC-induced coronary endothelial protection against IR injury.