Regulate HIF-1α On The Protective Effect On Myocardial Mitochondria After Ischemia Reperfusion In Aged Mice

Objective: The purpose of this study was to(1)compare whether young mice and old mice have differences in myocardial injury after ischemia/reperfusion,and determine whether naturally aged myocardium is more sensitive to ischemia/reperfusion injury;(2)HIF-1α was stably expressed in mice by AAV9 gene transduction,and HIF-1α could reduce the damage caused by ischemia/reperfusion to the myocardium.(3)To elucidate that HIF-1α regulates downstream HKⅡ level and protects aging myocardium by protecting mitochondrial structure and function;(4)To clarify that HKⅡ,as a biomarker,is associated with the prognosis of patients undergoing off-pump coronary artery bypass grafting,and can predict the incidence of major cardiovascular adverse events within 6months after surgery.Methods: Part 1: I/R model of male C57BL/6J mice aged 4 months and 18 months was established after HIF-1α was statically expressed by AAV9.Cardiac function indexes,myocardial infarction area,serum CK-MB and CTnl levels,myocardial cell structure,myocardial cell apoptosis rate and apoptosis-related protein levels were determined.To investigate the difference of myocardial injury between young mice and old mice and whether stable expression of HIF-1α can provide good myocardial protection.Part Two: After stable expression of HIF-1α in 18-month-old male mice,HKⅡ inhibitor3 Br PA was applied at I/R.Myocardial function index,myocardial infarction area,serum CK-MB and CTnl levels,myocardial cell structure,myocardial cell apoptosis rate,mitochondrial structure and function(mitochondrial ultrastructure,mitochondrial membrane potential △ ψm,m PTP)were determined Openness and ATP content),HIF pathway-related signaling molecules(HIF-1α,HK-ⅱ),and apoptosis-related proteins LC3,Bax,Bcl-2,Caspese-9,Caspase-3,Cyt-C protein expression levels.To further study the protective effect of HIF-1α/HKⅡ signaling pathway on aging myocardium.Part III: 120 patients undergoing off-pump coronary artery bypass grafting were selected,and serum CTnl,Cyt-C,IL-6 and HK-ⅱ levels were detected by ELISA.To evaluate the relationship between HKⅡ combined with Cyt-C and IL-6 detection and prognosis of patients undergoing off-pump coronary artery bypass grafting and the value of predicting complications within 6 months after surgery.Results: The HIF-1α level of old rats was lower than that of young rats after the same condition I/R,the myocardial infarction area was larger,the myocardial injury markers were higher,the apoptosis rate of myocardial cells was higher,and the apoptosis-related protein content was higher.Both young and old mice showed myocardial protective effect after stable expression of HIF-1α by AAV-9virus transduction,but the myocardial protective effect of young mice was more obvious than that of old mice.Stable expression of HIF-1α in elderly mice can up-regulate the expression of downstream target gene HKⅡ,and affect the expression of key apoptosis-related proteins,reduce myocardial infarction size,protect mitochondrial integrity,and improve cardiac function.The aggravation of myocardial injury and cell apoptosis in elderly rats after the use of HK-ⅱ inhibitors,suggesting that HIF-1αalleviates myocardial I/R injury in elderly rats through HIF-1α/ HK-ⅱ signaling pathway.The levels of CTnⅠ,Cyt-C,IL-6 and HKII in patients undergoing off-pump coronary artery bypass grafting at admission and three days after surgery were compared,and the postoperative levels were significantly higher than those before surgery,confirming that perioperative ischemia/reperfusion injury did indeed cause myocardial injury.HKⅡ as a biomarker combined with Cyt-C and IL-6 can predict the short-term prognosis of patients undergoing off-pump coronary artery bypass grafting..Conclusions:(1)There are differences in myocardial injury between young and old mice after acute ischemia/reperfusion injury.The content of HIF-1α in old mice is lower,and the myocardial I/R injury is more severe than that in young mice,which can not play the role of myocardial protection through HIF-1α/HKⅡ signaling pathway.(2)HIF-1α can inhibit the opening of m PTP by activating HIF-1α/HKⅡ signaling pathway,stabilize mitochondrial membrane potential,protect mitochondrial integrity,and reduce myocardial injury caused by myocardial ischemia-reperfusion in elderly mice.(3)HKⅡ,as a biomarker,is associated with prognosis and outcome of patients undergoing off-pump coronary artery bypass grafting.Combined with Cyt-C and IL-6 detection,it can predict the incidence of postoperative severe complications.