| ObjectiveLimb ischemia-reperfusion could cause ischemia-reperfusion injury in limb locally,also in remote organs or tissue far from the limb,and heart is one of those mostly liable to be injuried.Limb ischemic postconditioning(LIPos)and remifentanil could attenuate myocardial ischemia-reperfusion injury(MIRI)significantly.The mechanism of them two have partially the same pathway,such as reducing oxygen free radicals,restraining lipid peroxidation and calcium overload,inhibiting apoptosis, augmenting the release of nitric oxide,activating protein kinase C and mitochondrial ATP-sensitive potassium channels and mitogen activated protein kinase and opioid receptor.Studies have focused on the protective effects of LIPos on MIRI in the past. In this animal experiment limb ischemia-reperfusion model in vivo was established to exploring the effects of LIPos and the combination of remifentanil and LIPos on the whole body and on myocardium without suferring from ischemia and reperfusion, and to investigate if remifentanil could enhance the protective effect of LIPos.MethodsThirty-two Wistar rats were randomly divided into 4 groups(n=8):a sham operation group(Group S),a limb ischemia reperfusion group(Group LIR),a limb ischemic postconditioning group(Group LIPos)and a combination of remifentanil and limb ischemic postconditioning group(Group RLIPos).The in vivo rat model of limb ischemia-reperfusion injury was established with ischemia by occluding femoral artery and femoral vein for 60 minutes and repefusion by unclamping those for 120 minutes.During reperfusion 4 times brief ischemia and reperfusion of LIPos were performed,and remifentanil was administered intermitenfly via intraperitoneal injection using micro-injection pump.After 120 minutes reperfusion 5 milliliter blood was gathered from abdominal aorta respectively,then supematant fluid was collected after centrifugalization,and rat heart was removed and immersed into 10%liquor formaldehyde immediately.Serum activity of superoxide dismutases(SOD)and malondialdehyde(MDA),serum levels of glutamic-oxalacetic transarninase(AST)and glutamate-pyruvate transaminase(ALT)were determined respectively.The structural changes of myocardium was examinated by microscopy with HE staining.Results(1)Compared with Group S,serum SOD activity was not changed(P＞0.05)in Group LIR,and it was increased remarkably in Group LIPos and Group RLIPos,but there were no statistical difference between them(P＞0.05),and serum MDA activity was increased significantly(P=0.01)in Group LIR.Compared with Group LIR,serum MDA activity were decreased remarkably in Group LIPos and Group RLIPos(P＜0.05).SOD activity and MDA activity were similar both in Group LIPos and Group RLIPos(P＞0.05).(2)It was founded that serum AST content was higher in both Group LIR and Group LIPos(P＜0.05),but it was no remarkable difference between Group S and Group RLIPos than that in Group S(P＞0.05),and it was no significant difference between Group LIR and Group LIPos(P＞0.05).(3)The changes of serum ALT content was the same as those of the serum AST content in all 4 groups accordingly.(4)The structural changes of myoeardium was similar with each other and there were no pathological changes remarkably in all groups.ConolusionLIPos and the combination of remifentanil and LIPos could protect organism against limb ischemia-reperfusion injury in rats and remifentanil could enhance the protective effects of LIPos.The mechanism might be related to strengthening antioxidation action and to decreasing lipid peroxidation injury and to activating opioid receptors.But LIPos could increase serum AST and ALT levels with potential injury to myocardium.However,the combination of rernifentanil could attenuate the effect above all significantly.
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