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 of underlying ischemia-reperfusion injury of the heart.To investigate the protective effects of pharmacological preconditioning(PPC)and ischemic preconditioning(IPC)on ischemia-reperfution injury and to search the clinical value.Methods:The heart 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-reperfusion,ischemic preconditioning was achieved with stimulus of local ischemia for 5 minutes followed by 5 minutes reperfusion.(Ⅲ)Adenosine preconditioning group(Adopc).The rabbits were received a 5 minutes infusion of adenosion(2 mg/kg)before ischemia-reperfusion.(Ⅳ) Norepinephrine preconditioning(NEPC)a 5 minutes infusion of norepinephrine(0.25 μg/kg)was given before ischemia-reperfusion.Observed indexes include:①myocardial contractility.②the incidence of arrhythmia.③CK in blood.④myocardial SOD and MAD.⑤myocardial ultrastructure observation.Results:The results showed that Ⅱ、Ⅲ、Ⅳgroup,Significantly improved myocardial contractility(±dp/dtmax)as compared with Ⅰ group during reperfusion period(P0.05),but comparing±dp/dtmax amang group.The incidence of reperfusion arrhythmia was higher in group Ⅱ、Ⅲ、Ⅳthan in group Ⅰ(P0.01).CK leakage wasremarkably reduced in group Ⅱ、Ⅲ、Ⅳ(P0.05).Myocardial SOD was higher in groupⅡ、Ⅲ、Ⅳthan in groupr Ⅰ(P0.05).myocardial electron microscope observationdemonstrated that myocardial ultrastucture of group Ⅱ、Ⅲ、Ⅳwas better than of group I.Conclusion:This study suggested pharmacological preconditioning(PPC)and ischemic preconditioning(IPC) can remarkably enhance cardio-protecive 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.