Protective Effects Of Pharmacological Preconditioning And Ischemic Preconditioning On Ischemic-reperfusion Injury In Rabbit Heart

Objective: The purpose of this study is to explore the mechanisms underlying ischemia-reperfusion injury of the heart. To investigate the protective effects of pharmacological preconditioning (PPC) and ischemic preconditioning (IPC) on ischemia-reperfusion injury and to search the clinical value.Methods: The hearts of rabbits were used to made ischemia-reperfusion model in our experiment. All hearts were subject to 20 minutes local ischemia; then were reperfused for 30 minutes. Forty rabbits were randomly divided into four groups: ( I ) Sham control group (SC); (II ) Ischemic preconditioning group (IPC), before ischemia-reperflision, ischemic preconditioning was achieved with stimulus of local ischemia for 5 minutes followed by 5 minutesreperfusion. (III) Adenosine preconditioning group (AdoPC). The rabbits were received a 5-minute infusion of adenosine (2mg/kg) before ischemia-reperfusion. (IV) Norepinephrine preconditioning (NEPC) a 5-minute infusion of norepinephrine (0.25ug/kgmin) was given before ischemia-reperfusion. Observed indexes include: (I) myocardial contractility (2) the incidence of arrhythmia (3) CK in blood (4) myocardial SOD and MDA (5) myocardial ultrastructure observation.Observed indexes include: (I) myocardial contractility (2) the incidence of arrhythmia (3) CK in blood (4) myocardial SOD and MDA (5) myocardial ultrastructure observation. Results: The results showed that II groups III groups IV group significantly improved myocardial contractility (±dp/dtmax) as compared with I group during reperfusion period.(p<0.05),but comparing 眃p/dtmax among group II, III, IV , there was no significant difference. The incidence of reperfusion arrhythmia was higher in group II, III, IV than in group I (P>0.05). CK leakage was remarkably reduced in group II ,III, IV(P<0.05). Myocardial SOD was higher in group II,III, IVthan in group I (P<0.05).Myocardial MDA was less in group II , III, IV (P<0.05). Furthermore myocardial electron microscope observation demonstrated that myocardial ultrastructure of group II,III,IV was better than that of group I .Conclusion: This study suggested pharmacological preconditioning (PPC) and ischemic preconditioning (IPC) can remarkably enhance cardio-protective effects on ischemia-reperfusion injury. The cardio-protective effects of PPC and IPC were carried out by activating themselves endogenous protective mechanism. Especially pharmacological preconditioning posses potential clinical value . It will bring the hope for us to protect and treatment ischemia-reperfusion injury in clinical work.