Effect Of Oxycodone Postconditioning On Myocardial Ischemia-reperfusion Injury In Rats

Objective:To evaluate the Effect of oxycodone postconditioning on myocardial ischemia-reperfusion injury in rats.Methods:Fifty healthy adult male Sprague-Dawley rats,weighing 200-300 g,were randomly divided into 5 groups(n=10 each)using a random number table:sham operation group(group S),I/R group(group I),oxycodone postconditioning group(group O),κ receptor antagonist nor-binaltorphimine(Nor-BNI)group(group N),and PKC inhibitor chelerythrine group(group CH).The model of myocardial I/R was established by 30 min occlusion of anterior descending branch of left coronary artery followed by 120 min reperfusion.In group S,the anterior descending branch was only exposed but not ligated;In N and CH groups,Nor-BNI 2mg/kg and chelerythrine 5mg/kg were respectively injected intravenously before LAD ligation.In O,N and CH groups,oxycodone 0.5 mg/kg was injected intravenously at 2 min prior to reperfusion.The serum levels of cardiac troponin I(cTnI)and creatine kinase isoenzyme MB(CK-MB)in plasma were measured at the end of reperfusion.The hearts were removed at 120 min of reperfusion for determination of myocardial infarct size(Infarct size was determined by 2,3,5-triphenyltetrazolium chloride staining).Results:Compared with group S,the activities of serum cTnI and CK-MB were significantly increased and the percentage of myocardial infarct size was increased in I,O,N and CH groups(P<0.05).Compared with group I,the activities of serum cTnI and CK-MB were significantly decreased,the percentage of myocardial infarct size was decreased in O,N and CH groups(P<0.05).Compared with group O,the activities of serum cTnI and CK-MB were significantly increased and the percentage of myocardial infarct size was increased in N and CH groups(P<0.05).Conclusion : Oxycodone postconditioning can mitigate myocardial ischemia-reperfusion injury in rats,and the mechanism is related to activation ofк-opioid receptor and PKC channel.