| Objective: Cardiovascular disease is currently a prominent social medical problem worldwide,and its prevalence continues to rise.It has become the leading cause of death worldwide.Diabetes is an important risk factor for cardiovascular disease.The risk of myocardial ischemia-reperfusion injury in patients with ischemic heart disease with diabetes is two to three times that of patients with non-diabetic ischemic heart disease.Sevoflurane Postconditionning(SPostC)can effectively alleviate ischemic injury of healthy myocardium,but the cardioprotection of SpostC is weakened in the diabetic state.Previous studies have confirmed that the weakened protective effect of sevoflurane postconditioning in diabetic state may be due to impaired HIF-1 signaling pathway.DFO can activate impaired HIF-1α in diabetic state to restore the protective effect of sevoflurane,but the specific mechanism is unclear.Recent studies have found that mitochondrial autophagy is involved in myocardial protection of sevoflurane postconditioning.However,mitochondrial autophagy is inhibited in the diabetic state.How to reappear the myocardial protective effect of SPostC in diabetes is an important clinical problem.Whether HIF-1α/BNIP3-mediated mitochondrial autophagy is involved in restoring the protective effect of sevoflurane postconditioning in diabetic conditions is particularly important.The purpose of this study is to investigate the role of HIF-1-regulated mitochondrial autophagy in the protection of SPostC against ischemic myocardial injury,and to restore the cardioprotection of SpostC in diabetic state by regulating HIF-1-mediated mitochondrial autophagy.Methods: At the ex vivo level of,establishment H9C2 cardiomyocyte hypoxia/reoxygenation model,and received 2.4% sevoflurane postconditionning at the beginning of reoxygenation.Cell viability,LDH activity,apoptotic rate and autophagosomes were observed;HIF-1α,BNIP3,and Beclin-1 protein expressions were detected by western blot.In vivo level,I/R model was established by ligating the anterior descending coronary artery of rats for 40 minutes,and then reinfusion for 120 minutes.DFO(200mg/kg)was injected intraperitoneally 24 hours before ischemia,1MAC sevoflurane was administered at the first 15 minutes of reperfusion.The myocardial infarct size,ultrastructure of mitochondria,autophagosome,ATP content,membrane potential,ROS production rate,HIF-1α,BNIP3,LC3-II,Beclin-1,P62,LAMP2 protein expression and cardiac function were measured after 2h reperfusion.Results: Cell experiment after hypoxia-reoxygenation injury,compared with the H/R group,SpostC can up-regulate the expression of HIF-1α and BNIP3 proteins(P<0.05,SPostC group vs H/R group),promote the elimination of autophagosomes,significantly increase cell viability,and reduce LDH,but this protection is eliminated by 2ME2 or sinBNIP3.In diabetic state,compared with the I/R group,the protection effect of the SpostC group was weakened.After DFO treatment,SPostC up-regulated the protein expression of HIF-1α and BNIP3(P<0.05),reduced the expression of LC3B-II,Beclin-1,P62 and increased the expression of LAMP2.Furthermore,autophagosome accumulation decreased significantly,ROS production rate decreased,ATP content increased significantly,membrane potential increased,myocardial infarction area decreased significantly,and cardiac function improved significantly(P<0.05,SPostC group vs DFO+SpostC group).Conclusion: SPostC regulates HIF-1α/BNIP3 signaling pathway to promote mitochondrial autophagy and reduce myocardial cell hypoxia and reoxygenation injury.SPostC can up regulate the expression of HIF-1 α,further intensify the downstream target gene BNIP3,promote the mitochondrial autophagy mediated by BNIP3,eliminate autophagy bodies and increase cell viability,reduce LDH level,inhibit cell apoptosis,and finally resist cell hypoxia reoxygenation injury.DFO combined with SPostC can activate impaired HIF-1α and up-regulate HIF-1α protein expression,further promote HIF-1α/BNIP3-mediated mitochondrial autophagy and promptly remove damaged mitochondria.As a result,damaged mitochondrial-derived ROS was reduced,ATP content was increased,mitochondrial membrane potential was stabilized.Finally,myocardial infarct size was reduced,and cardiac function was improved in diabetic state. |
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