| Objective:To evaluate the effect of oxycodone postconditioninging on myocardial Ischemia-reperfusion injury induced by myocardial ischemia-reperfusion in rabbits and the role of ?opioid receptors.Methods:Male rabbits,aged 2~3 months,weighing 2.2~2.8 kg,establishing the model of myocardial ischemia-reperfusion injury by occlusion of the left anterior descending branch of coronary artery for 30 min followed by 180 min reperfusion,were randomly divided into 5 groups using a random number table : 1)sham operation group(group Sham,n=8): left anterior descending branch thread only,not ligated;2)ischemia-reperfusion group(group I/R,n=9): 30 min ischemia and 180 min reperfusion only without other intervention;3)Ischemia Post-conditioning group(group Ipoc,n=9): at the first three minutes of reperfusion,three cycles of a 10 s reperfusion interspersed with a 10 s ischemia preceded 180 min reperfusion;oxycodone postconditioning(group Oxpoc,n=9): oxycodone,0.3mg/kg,was injected intravenously at 5 min before reperfusion;? receptor antagonist nor-binaltorphimne + oxycodone postconditioning group(group BNI + Oxpoc,n=10): BNI was given 10 min prior to reperfusion and the rest of treatments as the same as Oxpoc group.Venous blood samples were collected at the end of reperfusion for measurement of the plasma cTnI and CK-MB concentrations.The rabbits were then sacrificed and the heart tissue was adopted for the later determination.TTC staining was used to detect the myocardial infarct size and immunohistochemical staining was used to detect the expression of Cx43 protein in myocardial cells.Results:Compared with Sham group,cTnI and CK-MB in the other four groups were increased(P<0.05)and the value of Cx43 OD were decreased(P<0.05);Compared with I/R group,IS/LVS,cTnI and CK-MB concentrations were decreased in Ipoc and Oxpoc group(P < 0.05),and Cx43 OD were increased in Ipoc and Oxpoc group(P < 0.05);Compared with Ipoc group or Oxpoc group,IS/LVS,cTnI and CK-MB concentrations were increased and Cx43 OD were decreased in BNI+Oxpoc group(P<0.05).Conclusions:1.Oxycodone can protect the heart from myocardial ischemia/reperfusion injury when administered at the onset of reperfusion and just as effective as ischemia post-conditioning and the mechanism may be associated with the activation of ? receptors.2.The myocardial protection of oxycodone postconditioning may regulated the expression of Cx43 through activated ? opioid receptors. |
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