Study Of Interval Exercise Training On Protective Effect Of Cardiac Ischemia/reperfusion Damage And Its Mechanism

When people have severity sports, cardiac function often be impaired because ofrelative ischemia, myocardium sometimes be injured. Blood stream resuming afterischemia will put cardiac function and reversibility structure damage right. Butexperiments studies discovered that blood stream resuming after brief ischemiacaused myocardium injured worse because of ischemia-reperfusion injury ofmyocardium. Ischemia precondition a available way to lighten myocardium injuryinduced by ischemia-reperfusion. IPC is a phenomenon by which a brief episode(s) ofmyocardial ischemia increases the ability of the heart to a subsequent prolongedperiod of ischemic injury. There are some researches relate to exercise precondition(EP), but its mechanism keep unknown. In this study, we want to investigate thecardioprotective effect, relational cellular and molecular mechanisms of chronicinterval training and acute interval exercise preventing ischemia-reperfusion injury ofmyocardium by Sprague-Dawley rats models was established by occlusion the coronaryartery in vivo. The study aim at offer experiment evidence for search a safe andeffective means without ravage.1. The effect of interval exercise on ischemia-reperfusion rats' myocardium andcardiac function.The model of ischemia-reperfusion injury of rat myocardium in vivo were inducedby ligateing left coronary artery. By observe the effect of high-intensity intervaltraining and once high-intensity interval exercise on myocardium, ECG and serumenzyme from myocardium; confirm the cardioprotection of high interval exercise.42 rats were randomly divided into four groups. 8 rats from every group thatsucceed being made model were bring into experiment. The rats in CONT+I/R GROUP from sedentary group were subjected to 30min of left anterior descendingcoronary artery (LAD) occlusion followed by 40min reperfusion. The rats inCONT+SHAM GROUP from sedentary group were operated as CONT+I/R GROUPbut didn't ligate LAD. The rats in IT+I/R GROUP were from interval training groupand the rats in OIE+I/R GROUP were from once interval exercise group, theoperation as CONT+I/R GROUP.The purposes of the study is having histopsthologic examination of myocardium inrats and observe developmental ECG, index of cardiac function and myocardiumenzyme in serum.The data showed that interval training make hearts of rat hypertrophy. The extent ofpathologic change in IT+I/R GROUP and OIE+I/R GROUP is less than that inCONT+I/R GROUP. At the time of ischemia 30min and reperfusion 40min, rise ofST(J point) and activities of CK, LDH and GOT in IT+I/P, GROUP is notable lessthan CONT+I/R GROUR But cardiac function in IT+I/R GROUP is significant higherthan CONT+I/R GROUP. Above index in OIT+I/R GROUP almost like IT+I/RGROUP, only GOT, LVDP and +dp/dt_max without significant changes compare withCONT+I/R GROUP.The result indicated interval training and once interval exercise play an importantrole in the late phase of IPC. And the effect of high-intensity interval training isstronger than once high-intensity interval exercise.2. The effect of interval exercise on ischemia-reperfusion rats' myocardiumantioxidant defenses capabilityThe experiment aim at exploring use and mechanism of free radical defensessystem in interval exercise mediated cardioprotection against ischemia-reperfusioninjure.The model and grouping was used as previously described. Suitable myocardiumwas taken to examine MDA, SOD and GSH-Px by colorimetry after 30min ischemiaand 40min reperfusion.The data showed that activities of SOD and GSH-Px are notable higher in IT+I/R GROUP and OIT+I/R GROUP than CONT+I/R GROUP, but content of MDA issignificant less than CONT+I/R GROUP.The result indicated interval exercise increase antioxidant defenses capability in I/Rmyocardium, considering cardioprotection from interval exercise we presuming byreduction free radical damage and increase antioxidant defenses capability maybemediate cardioprotection of EP against I/R injury.3. The effect of interval exercise on ischemia-reperfusion rats' myocardiumendogenous protective factorsThe experiment study NO and HSP70, aim at exploring use and mechanism ofendogenous protective factors in interval exercise mediated cardioprotection againstischemia-reperfusion injure.The model and grouping was used as previously described. Suitable myocardiumwas taken to examine NO and NOS by colorimetry, Expression Levels of HSP70 byimmunohistochemical and Western Blot means after 30min ischemia and 40minreperfusion.The data showed that content of NO and activity of cNOS is higher in IT+I/RGROUP than CONT+I/R GROUP, but activity iNOS is less than CONT+I/R GROUP.Content of NO and activity of iNOS is higher in OIT+I/R GROUP than CONT+I/RGROUP, but activity cNOS is less than CONT+I/R GROUP. Expression Levels ofHSP70 in IT+I/R GROUP and OIT+I/R GROUP is significant higher than CONT+I/RGROUP.The result indicated interval training enhance myocardium ability against I/R injuryby increasing expression of cNOS but restraining expression of iNOS, increasing NOcontent. Once interval exercise mainly restrain expression of iNOS and reducetoxicity of NO. As molecular chaperone HSP70 participate in cardioprotection.4. The effect of interval exercise on ischemia-reperfusion rats' cardiac myocyteapoptosis and correlative regulation geneThe experiment examine cardiac myocyte apoptosis and correlative regulation gene,aim at exploring effect of interval exercise precondition on cardiac myocyteapoptosis. The model and grouping was used as previously described. Suitable myocardiumwas taken to examine DNA Ladder by gel electrophoresis, apoptosis degree byTUNEL, expression of Bcl-2/bax by RT-PCR.The data showed that apoptosis degree in IT+I/R GROUP and OIT+I/R GROUP issignificant less than CONT+I/R GROUP. Interval training promote gene expression ofBcl-2 and restrain gene expression of bax. Once interval exercise only promoteexpression of Bcl-2.The result indicated interval training and once interval exercise efficiently restraincardiac myocyte apoptosis in I/R heart by altering expression of regulation gene.Thereby precondition come forth.5. The effect of interval exercise on ischemia-reperfusion rats' cardiac myocyteapoptosis and correlative regulation geneThe experiment at the point of signaling transduction, aim at exploring station andmechanism of protein kinase C in interval exercise mediated cardioprotection againstischemia-reperfusion injure.The model and grouping was used as previously described. Suitable myocardiumwas taken to examine PKC protein by immunohistochemical means, examinePKCmRNA expression by RT-PCR technique.The data showed that expression of PKC in IT+I/R GROUP and OIT+I/R GROUPis significant higher than CONT+I/R GROUP.The result indicated interval training and once interval exercise efficiently activatePKC and its' expression. Cardioprotection induced by interval training and onceinterval exercise maybe mediated by PKC signal pathway.