The Role And Mechanism Of ALCAT1 In Myocardial Infarction Rats In Inhibiting Abnormal Calcium Metabolism And Apoptosis Of Myocardial Cells By Exercise

Objectives:Discussed the effects of acyl-CoA:lysocardiolipin acyltransferase-1(ALCAT1)of myocardium and circulatory system and in the myocardial infarction rats.Methods:The experimental animals were 45 male SD rats,aged 3 months and weighted 180-220g(the level is SPF,purchased from Animal Experimental Management Center of Xi'an Jiaotong University,Animal Certification No:SCXK 2016-003).All rats were divided into seven groups,randomly:Control group(C),Sham-operated group(S),Group 1 hour after MI(MI-1),Group after MI 6 hours(MI-6),Group 12 hours after MI(MI-12),Group 24 hours after MI(MI-24)and Group 5 days after MI(MI-5d).After the surgery,alived 56 rats which every group have 8 rats.Rat eated with national standard foods.In addition,another 70 male SD rats which aged 3 months were divided into 5 groups,randomly:Control group(C),Sham-operated group(S),Myocardial Infarct group(MI),Control+Exercise group(CE)and Myocardial Infarct+Aerobic Exercise group(ME),every group has 8 rats.The rats which were operated were ligated the left anterior descending coronary artery(LAD).After 24 hours,the operated rats randomly were divided into MI and ME.The aerobic exercise was started after lweek after the operation of MI.CE group and ME group go on 4 weeks aerobic exercise.Firstly,the training began at 10m/min×10min to make rats adapt the training.Then,we added the strength to 13m/min×10min.Finally,we selected the strength at 16m/minx40min.Rat was training for 1hour every day and 5 days every week,exercise was going-on 4 weeks.Rat which was of the C group,S group and MI group was feeded for 4 weeks,no training.After 4 weeks,rat was treated abdominal anaesthesia and was supervised ECG,hemodynamic indexes to assess the cardiac function.After that,the abdominal aorta was extracted and the heart was extracted and used for later experiments.All rats were fasted for 24 hours.Ionoptix was used to measure the systolic function and cardiomyocyte calcium transient;The percentage of Collagen volume fraction(CVF)was observed by Masson staining to supervise the CVF,Caspase 3 kit tests the apoptosis of myocardial cells;Kit was used to test myocardial and serum antioxidant capacity;Western Blot was used to test the proteinic expression level of ALCAT1,BNP,SOD1,SOD2,PKG,PLN,SERCA2a,Akt,p-Akt,Cyt C,Bcl-2,Bax,PI3K,p-PI3K;Using the RT-qPCR to test the lclatl mRNA expression.Results:(1)The proteinic expression level of ALCAT1 in MI-1h,MI-6h,MI-12h,MI-24h and MI-5d groups significantly of myocardium and in MI-1h and MI-6h of serum was upregulated.It was indicated that myocardial infarction resulted in significantly increasing the ALCAT1 proteinic expression of the myocardial and serum in rats,and after operation lh-6h,the ALCAT1 index in the serum was a marker for early diagnosis of myocardial infarction.(2)Myocardial infarction caused serious damage to the heart of rats.The testing effect of the serous CK,CKMB in MI 24h was remarkable,and LDH index was not restricted by 24h change,still can be determined the 5d,effectively,after myocardial infarction.It was reflected that myocardial injury which caused by MI was sustainable.Simultaneously,the rat's myocardium occured fibrosis in 5 days after myocardial infarction.(3)The proteinic level of ALCAT1 was significantly increased in the myocardium and the serum in myocardial infarction rats.And the four-week aerobic exercise significantly reduced the myocardial and serous proteinic level of ALCAT1 in myocardial infarction rats.(4)The myocardial and serous antioxidant capacity of the myocardial infarction rats was significantly reduced.Nevertheless,4-week aerobic exercise can significantly increase SOD level,restrain the lipid peroxidation products MDA level of cardiac muscle and serum,improve its oxydic resistance.(5)Myocardial infarction caused the generation of myocardial collagen fiber and heart function damage,4 weeks aerobic exercise could inhibit the excessive generation of myocardial collagen fibers,and improve heart function.(6)4 weeks aerobic exercise could significantly inhibited the myocardial apoptosis in myocardial infarction rats.Aerobic exercise significantly reduced the myocardial Caspase 3 activity(P<0.05)and Cyt C and Bax proteinic expression(P<0.01,P<0.05),significantly increased the Bcl-2 expression and the Bcl-2/Bax ratio(P<0.01).It was indicated that myocardial apoptosis was significantly increased in the myocardial infarction rats,and aerobic exercise could significantly inhibit myocardial apoptosis.(7)4 weeks aerobic exercise notably improved the calcium transient of myocardial cells in myocardial infarction rats.Aerobic exercise prominently increased the Ratio amplitude,[Ca2+]i amplitude,Departure velocity and Return velocity values in normal myocardial cells(P<0.01),significantly reduced the TTP,TTP50%and TTB50%(P<0.01,P<0.05);The Ratio amplitude,[Ca2+]i amplitude,Departure velocity and Return velocity values were significantly reduced(P<0.01),the values of TTP,TTP50%and TTB50%were prominently increased in the myocardial cell of the myocardial infarction(P<0.01).Aerobic exercise reversed the index changes significantly.It was shown that cardiac infarction resulted in the abnormal Ca2+ regulation in the single myocardial cell of rats,and the amplitude and rate of calcium transient were significantly decreased.Aerobic exercise could effectively improved the calcium transient of myocardial cells in myocardial infarction rats.(8)4 weeks of aerobic exercise significantly improved the systolic function of myocardial cells in myocardial infarction rats.Aerobic exercise a significant rise in a single normal myocardial cells of sarcomere PTA,SL Shortening%,plus or minus value of dl/dtmax(P<0.01),the above indexes after myocardial infarction were significantly lower(P<0.01),aerobic exercise were significantly improve the above indexes(P<0.01,P<0.05).It is shown that myocardial infarction can significantly improve the contractility of individual myocardial cells after aerobic exercise intervention.(9)4 weeks aerobic exercise significantly increased myocardial PI3K-Akt-PKG-PLN-SERCA2a pathway.Aerobic exercise notably increased the normal myocardial proteinic expression of the PKG-1,p-PI3K,SERCA2a signaling pathway(P<0.01,P<0.05).Myocardial infarction significantly increased the myocardial proteinic expression of the p-PI3K and p-AKT protein(P<0.01,P<0.05),prominently down-regulated the proteinic expression of the PKG-1 and SERCA2a protein(P<0.01,P<0.05).The expression of the p-PI3K,p-AKT and SERCA2a protein in myocardial infarction were significantly increased(P<0.01,P<0.05).It was shown that the myocardial PI3K-Akt-PKG-PLN-SERCA2a signaling pathway was inhibited,and aerobic exercise significantly activated the signaling pathway.Conclusions:(1)The proteinic expression of ALCAT1 had a time stages effection in the heart.Myocardial infarction resulted in a significant increase of the ALCAT1 proteinic expression in the myocardium and serum of rats.And the serous ALCAT1 protein was a marker for early diagnosis of myocardial infarction after MI 1-6h.Four weeks aerobic exercise could significantly reduced the myocardial and serous ALCAT1 levels in normal and myocardial infarction rats.(2)4 weeks aerobic exercise could increased SOD level,significantly,and restrained the MDA level in cardiac muscle and serum,improved the antioxidant capacity,restrained the excessive myocardial collagen fibers and myocardial cell apoptosis,improved myocardial function.(3)Myocardial infarction resulted in the abnormal Ca2+ regulation of myocardial cells in rats,and decreased calcium transient amplitude and rate and the contractile ability of single myocardial cell,also inhibited myocardial PI3K-Akt-PKG-p-PLN-SERCA2a pathway.The 4-week aerobic exercise effectively improved the calcium transient and the contractile function of myocardial cells,and significantly activated the PI3K-Akt-PKG-pPLN-SERCA2a pathway.