| Objective: To compare the effects of cardioprotection by morphine andsufentanil preconditioning through the model of myocardial ischemic-reperfusioninjury of rabbits.Methods: Healthy male New Zealand rabbits were randomly divided into fourgroups, sham group (S, n=6), ischemia-reperfusion group (I/R, n=9), morphinegroup (MF, n=9) and sufentanil group (SF, n=9).The ischemic-reperfusion injurymodel was established by ligature the left ventricular branch of coronary artery.Group S: the artery was found and threaded but not ligatured; group I/R: ligaturedthe left ventricular branch for30min and reperfused for120min; group MF: morphine(1mg/kg) was injected through jugular vein before ligature,the next steps were sameas group I/R; group SF: sufentanil (1μg/kg) was injected through jugular vein beforeligature,the next steps were same as group I/R. Record heart rates and mean arterialpressures at baseline（T0）、the moment before ischemic(T1)、30min of ischemic(T2)、30min of reperfusion(T3)、60min of reperfusion(T4)and2h after reperfusion(T5).Blood was taken to test the concentration of creatine kinase MB and superoxidedismutase at the basal state and120min after reperfusion. Six rabbits were randomlyselected from each group (except for group S) to measure the ischemic size andinfarct size after reperfusion for120min; three rabbits were randomly selected fromeach group after reperfusion for3h,tissue specimens were harvested for HE stainingand apoptotic index examining.Results:(1)Hemodynamics：there were no significant differences of HR andMAP between each group at baseline. Compared with groups S and I/R，the HR andMAP were lower when morphine and sufentanil were infused（P＜0.05）;except forgroup S, the HR and MAP were lower at T2-T5than at T0（P＜0.05）;At T1, the HRof group MF was lower than group I/R（P＜0.05）;At T2、T3，the HR of group I/Rwere lower than group S（P＜0.05）; At T4,the HR of group I/R was lower than group S and group SF（P＜0.05）; At T5,compared with group S, the HR of other threegroups were lower（P＜0.05）.At T1,the MAP of group MF and SF were lower thangroup S and I/R（P＜0.05）;At T2-T5, compared with group S, the MAP of other threegroups were lower（P＜0.05）,but group MF and SF were higher than group I/R（P＜0.05）.(2)The concentration of SOD in serum: there were no significant differencesof SOD between each group at baseline. The concentration of SOD after reperfusionwere lower than that of baseline, except for group S（P＜0.05）; Compared with groupS, after reperfusion, the SOD of other three groups were lower（P＜0.05）;Theconcentration of SOD in group MF and SF were higher than group I/R（P＜0.05）.(3) The concentration of CK-MB in serum: there were no significantdifferences of CK-MB between each group at baseline. The concentration of CK-MBafter reperfusion were higher than that of baseline, except for group S（P＜0.05）;Compared with group S, after reperfusion, the CK-MB of other three groups werehighe（rP＜0.05）; The concentration of CK-MB in group MF and SF were lower thangroup I/R（P＜0.05）；In contrast to group MF，the concentration of CK-MB afterreperfusion was higher in group SF（P＜0.05）.(4)Myocardial infarct size：There were no significant differences of leftventricular mass and area at risk between each group（P＞0.05）.The infarct size ofgroup MF and SF were significant lower than group I/R（P＜0.01）；Compared withgroup MF，the infarct size was higher in group SF（P＜0.05）.(5)HE staining of ischemic tissue: Myocardial structure was normal in groupS，the myocardial pathological damage was the most serious in group I/R, group MFand SF receive a slighter myocardial damage in contrast with group I/R.(6)The apoptosis index of ischemic tissue：The apoptosis index was thehighest in group I/R and had a significant difference（P＜0.01）；The apoptosis indexwas higher in group SF than group MF（P＜0.01）.Conclusion:(1) Morphine and sufentanil preconditioning can providemyocardial protection through reducing ischemic-reperfusion injury；（2） Accordingto the creatine kinase isoenzyme, myocardial infarct size and apoptosis index, the cardioprotection against ischemic-reperfusion injury of morphine was better thanequivalent dose of sufentanil. |
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