The Study Of Protective Effects Of Double-limbs Ischemic Preconditioning And Ang-Ⅱ Ischemic Preconditioning On Ischemia-reperfusion Injury In Rat Heart

Objective: On Langendorff isolated rat heart model, to observe the protective effects of double limbs ischemic preconditioning,Ang-II ischemic preconditioning and complication with these two ways ,and find out the more effective and reasonable way to attenuate the injury.Methods: 32 healthy rats were divided into 4 groups randomly, 8 cases in every group; I group:sham control group (SC),after mensurate the basic data, kept refusion with K-H solution for 20 minutes, and then stopped affusing for 45 minutes , before 60 minutes reperfusion ; II group:Double limbs ischemic preconditioning group( DL-IPC), before reperfusion ,trussed the double limbs of rats with hemostatic band ,obstructed for 5 minutes then loosed for 5 minutes 4 times, after this ,we dealed with them like SC; III group: Ang-II group , after recording basic data, perfused with K-H solution for 10 minutes, then K-H solution+Ang-II(10-7mol/L) for 5 minutes, underwent local ischemic for 45 minutes before reperfusion for 60 minutes; IV group: DL-IPC+Ang-II IPC group, it was the same with III after precondion on double limbs. Observed indexes include: 1) myocardial contractility; 2) ECG; 3) incidence of arrhymia; 4) CK-MB in leakage of coronary artery; 5) myocardial water content; 6) myocardial ultrastructure observation.Results: The results demonstrated that double limbs ischemic preconditioning,Ang-II ischemic preconditioning and DL-IPC+AngII-IPC significantly improved myocardial contractility (dp/dtmas and LVSP) as compared with sham control group during reperfusion period, but comparing their protective effects among group II ,III,IV, there was no significant difference. The incidence of arrhymia was less in group II,III,IV than in group I(P<0.05). CK-MB in leakage was remarkably reduced in group II,III,IV (P<0.05). Furthermore myocardial eletron microscope observation showed that myocardial ultrastructure of group II,III,IV was better than that of group I, and group III and group IV appeared better than group II.Conclusion: These data suggested that double limbs ischemic preconditioning and AngII ischemic preconditioning can significantly enhance cardio-pretective effects on ischemia-reperfusion injury, but the synergetic effects of DL-IPC and AngII-IPC were not found. The protective effects of any methods in ischemic precondition(IPC) were carried out by activating themselves prêtective mechenism of organisms through some approach. The results can provide a new thought on selecting the way of IPC.