Effects Of Sufentanil Postconditioning On Myocardial Autophagy In Rats Ischemia Reperfusion Injury And The Role Of PI3k-Akt Pathway

Objective:To determine the effects of sufentanil postconditioning on myocardial autophagy and the role of phosphatidylinositol 3 kinase/ serine-threonine kinase(PI3K-Akt) signal transduction pathway in ischemia-reperfusion injury in rats.Methods:Thirty healthy male SD rats weighing 225-275 g were randomly divided into five groups(n=6) by random number table: sham operation group(S group); ischemiareperfusion group(I/R group); sufentanil postconditioning group(SP group); sufentanil postconditioning + Wortmannin group(SP+W group) and Wortmannin group(W group).The S group was received threading without ligation, whereas I/R group, SP group, SP+W group and W group were received by 30 min occlusion of left anterior descending branchofcoronary artery followed by 120 min reperfusion. At 5 min before reperfusion,these groups were respectively received by femoral vein injection of 1 ml saline,sufentanil(1μg/kg), sufentanil(1μg/kg) and PI3 K inhibitor Wortmannin(15μg/kg), or Wortmannin(15μg/kg) alone. At 120 min after reperfusion:(1)Arterial blood samples were collected and measured the serum c Tn I concentration by ELISA assay which could evaluate the severity of myocardial damage.(2) Observed mitochondrial damage and autophagysome in ischemia myocardial tissue under transmission lectron microscope.(3)Western blotting assay was used to detect the expression of Akt 、 p-Akt and autophagy-related protein Beclin-1 in ischemic myocardium, and calculated the p-Akt/Aktratio.Results:1. serum c Tn-I concentrationCompared with group S, serum c Tn-I the concentration of inseased serum c Tn-I, in group IR, SP and SP+W(P<0.05); serum c Tn-I concentration of group SP was lower than group IR(P<0.05); Compared with group SP, serum c Tn-I concentration inseased in group SP+W(P<0.05).2. Akt and p-Akt western blot analysisThe total Akt levels did not vary between study groups(P> 0.05). Compared with S group, the expression of p-Akt and the ratio of p-Akt/Akt were significantly higher in others groups(P<0.05); Compared with I/R group, the expression of p-Akt and the ratio of p-Akt/Akt were significantly higher in SP group(P<0.05); Compared with SP group, the expression of p-Akt and the ratio of p-Akt/Akt were significantly lower in SP+W group(P<0.05).3. Beclin-1 western blot analysisCompared with S group, the expression of Beclin-1 in others groups was significantly higher(P<0.05); the expression of Beclin-1 in SP group was lower than group IR(P<0.05);the expression of Beclin-1 in SP+W group was higher than group SP(P<0.05).4. Autophagosomes under transmission lectron microscopeIt’s difficult to find autophagosome in S group, but in the other groups we found the architecture of mitochondria was blurred,with the destructive mitochondrial crest and the number of autophagosomes increased under transmission lectron microscope.Conclusion:Sufentanil postconditioning reduce myocardial ischemia /reperfusion injury may by inhibiting the occurrence of autophagy during in reperfusion period, which may be associated with the pathway of PI3K/Akt.