| Objective : To study the protective effects of Edaravone on myocardial ischemia-reperfusion injury in rabbits and its mechnaism.Methods:Forty-eight New Zealand rabbits were randomly divided to three groups (n=16):the sham operated group(A group),the ischemia-reperfusion group(B group),the edaravone treatment group(C group).Rabbits were anesthetized intravenously with 1% pentobarbital sodium(30mg/kg),set up the left femoral vein access to inject drugs and draw off blood.The changes of ST segment in electrocardiogram were observed during the experiment.The sham operated group:open chest and expose heart,achieve full operation,left anterior coronary descending branch only was exposed but not was ligated,drip saline(5mg/kg) through the femoral vein 45 min later,finish the injection in 10 min,then observe the rabbits for 120 min.The ischemia-reperfusion group:ligate the left anterior coronary descending branch for 45 min,drip saline(5mg/kg) through the femoral vein and reperfusion for 120 min.The edaravone treatment group:edaravone(5mg/kg) replace saline.Then suture the chest wall to restore natural breathing.5 min before ligation,45 min after ligation,60 min after reperfusion and 120 min after reperfusion,4ml blood was drawn from left femoral vein to measure the amount of creatine kinase MB(CK-MB),serous troponin I(cTnI) and malondialdehyde(MDA),the activity of superoxide dismutase(SOD).At the end of reperfusion,infarct size of eight rabbits was assessed by weight after Evans blue-TTC staining in B group and C group;the other eight rabbits were observed morphological changes of myocardial tissue through optical microscope,ultrastructural changes of myocardial tissue through electricity microscope.Results:(1)After 45 min of ischemia,the amount of CK-MB and cTnI in serum in ischemia-reperfusion group and edaravone treatment group increased(compared with that before ischemia,P<0.05),increased rate of the two groups had no significant difference(P>0.05),after 60 min of reperfusion and 120 min of reperfusion,the amount of CK-MB and cTnI in serum increased further;The level of CK-MB and cTnI were significantly lower in edaravone treatment group than in ischemia-reperfusion group after reperfusion 60 min and 120 min(P<0.05).(2)After 45 min of ischemia,the activity of SOD in serum in ischemia-reperfusion group and edaravone treatment group decreased(compared with that before ischemia,P <0.05),and the amount of MDA increased(compared with that before ischemia,P<0.05),decreased and increased rate of the two groups have no significant difference(P> 0.05);after reperfusion 60 min and 120 min,the activity of SOD in ischemia-reperfusion group decreased further(compared with that before ischemia and that after 40 min of ischemia,P<0.05),the activity of SOD in edaravone treatment group increased than before;the amount of MDA increased further,the level of MDA were significantly lower in edaravone treatment group than in ischemia-reperfusion group(P < 0.05).(3)Myocardial infarct size of edaravone treatment group is (35.01±4.27)﹪compared with ischemia-reperfusion group is (55.53±5.91)﹪(P<0.01).(4)Morphology of myocardial tissue was observed with optics microscopes:myocardial tissue is nearly normal in sham group,but edaravone treatment group can reduced injury to myocardial tissue compared with that in ischemia-reperfusion group.(5)Myocardial ultrastructure:myocardial cells is nearly normal in sham group,edaravone treatment group can reduced injury to myocardial cells compared with that in ischemia-reperfusion group.Conclusions:Edaravone has protective effects on myocardial ischemia-reperfusion injury,it decreased significantly the amount of CK-MB,cTnI and MDA as well as increased the activity of SOD in serum.It also reduced injury in myocardial tissue and myocardial cells,which may be related to scavenging the oxygen free radicals during reperfusion,reduce the injury to myocardial tissue.
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