| Objective: To investigate the myocardial protection of Sufentanil postconditioning as well as to provide a help to explore medication for myocardial ischemia-reperfusion injury by measuring the level of cardiac troponin I,myocardial infarct size and cardiomyocyte apoptosis through the in vivo animal model of myocardial ischemia-reperfusion injury.Methods: 48 adult rats were randomly divided into four groups (12 rats each group) after anesthesia: sham-operation group (SHAM group), ischemia-reperfusion group (I/R group), ischemic postconditioning group (IPO group) and sufentanil postconditioning group (SUF group). The left anterior descending coronary artery (LAD) in all rats were ligated with slipknot by fine suture after thoracotomy, following treatments including 30 minutes'local myocardial ischemia and 120 minutes'reperfusion except in SHAM group. In SHAM group, the slipknot around LAD kept into loop for 150 minutes. In IPO group, LAD had been tied for 30minutes, followed by 120 minutes reperfusion, reperfusion was initiated for 20 seconds of reperfusion followed by 20 seconds of occlusion,repeated for 3 cycles. In SUF group, LAD had also been tied for 30minutes, while in the last 5 minutes of ligation, sufentanil postconditioning was with 1μg/kg i.v. slowly, followed by 120 minutes reperfusion. At the end of reperfusion, 6 rats were selected randomly in each group and 2ml blood was taken from rat right auricular to test the level of cardiac troponin I. Double-staining with Evans blue and Triphenyltetrazolium chloride was applied to measure myocardial infraction size (infraction size,IS%).Cardiac specimen was taken from the other 6 rats in each group, pathomorphology was examined with lens microscope. The expressions of Bax and Bcl-2 protein in the myocardium of ischemia area were measured by iummnohistochemical technique. Results:1. cTnI: Compared to SHAM group, the level of cTnI in I/R group, IPO group or SUF group increased markedly and significantly (P<0.001). Compared to I/R group, the level of cTnI in SHAM group, IPO group or SUF group decreased significantly (P<0.001),and there was not significant difference between IPO group and SUF group(LSD-t test ,P=0.363).2. Myocardial infarction size: No remarkable myocardial infarction was noted in SHAM group, there was no significant difference of left ventricular (LV) weight, myocardial area at risk (AAR) or ratio of AAR and LV (AAR/LV%) among the rest of three groups. Compared to I/R group, the weight of myocardial infarct size (IS) in IPO group and SUF group was significantly reduced(P=0.000),but there was no statistic difference between the IPO group and SUF group (LSD-t test, P=0.721). Compared to I/R group, IS/AAR% decreased markedly, either in IPO group or in SUF group, the difference was statistically significant (according to Nemenyi test,χ2=9.21, P=0.0100 in IPO group;χ2=7.95, P=0.0187 in SUF group). There was no significant difference of IS/AAR% between IPO group and SUF group (χ2=0.05, P=0.9772 by Nemenyi test).3. The expressions of Bax and Bcl-2 protein: Bax and Bcl-2 protein were rarely or normally expressed in SHAM group. Compared to SHAM group, the expressions of Bax or Bcl-2 protein increased remarkably in I/R group , IPO group and SUF group, the difference was significant (P<0.01). There was a marked expression of Bcl-2 protein in IPO group or in SUF group, compared to I/R group. Meanwhile, the expression of Bax protein decreased notably in IPO group or in SUF group, and there was no significant difference in the expression of Bcl-2 protein and Bax protein between IPO group and SUF group(Exact sig=0.026).Conclusions:Sufentanil postconditioning can alleviate myocardial ischemia-reperfusion injury in rat, decrease the level of cardiac Troponin I, reduce myocardial infarct size and lessen cardiomyocyte apoptosis, which indicates sufentanil postconditioning has noted effects on myocardial protection. |
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