Role Of ATP-sensitive K~+ Channels In Oxycodone Postconditioning-induced Attenuation Of Myocardial Ischemia-reperfusion Injury In Rats

Objective To evaluate the role of ATP-sensitive K+channels(KATPchannels)in oxycodone postconditioning-induced attenuation of myocardial ischemia-reperfusion(I/R)injury in rats.Methods Fifty healthy adult male Sprague-Dawley rats,aged 8-12 weeks,weighing200-300 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/R),oxycodone postconditioning group(group OP),oxycodone combined with κ receptor antagonist nor-binaltorphimine(Nor-BNI)group(group ON),and KATP channel blocker glibenclamide plus oxycodone postconditioning group(group GOP).Myocardial I/R was produced by 30 min occlusion of the anterior descending branch of the left coronary artery followed by 120 min reperfusion.In group S,the anterior descending branch was only exposed but not ligated;In ON and GOP groups,Nor-BNI 2mg/kg and glibenclamide1mg/kg were respectively injected via the jugular vein before ischemia.In OP,ON and GOP groups,oxycodone 0.5 mg/kg was injected via the jugular vein at 5 min prior to reperfusion,and the equal volume of normal saline was given in S and I/R groups.At 120 min of reperfusion,blood samples were collected from the carotid artery for determination of the level of serum cardiac troponin I(cTn I)and Lactic Dehydrogenase(LDH).The animals were then sacrificed,and the hearts were removed for determination of the myocardial infarct size in the left ventricle.Results Compared with group S,the concentration of serum cTnI,serum LDH and myocardial infarct size were significantly increased in I/R,OP,ON and GOP groups(P<0.05).Compared with group I/R,the concentration of serum c Tnl,serum LDH and myocardial infarct size were significantly decreased in OP,ON and GOP groups(P<0.05).Compared with group OP,the concentration of serum c TnI,serum LDH and myocardial infarct size were significantly increased in ON and GOP groups(P<0.05).Conclusion KATP channel opening is involved in oxycodone postconditioning induced attenuation of myocardial I/R injury in rats.