Intermittent Exercise Reduces Cardiac Oxidative Stress In Rats With Myocardial Infarction And Regulates Smyd1 Expression To Improve Cardiac Function

Objective:By investigating the intermittent exercise of Smydl gene and protein in non-infarcted myocardium of normal and myocardial infarction rats,analyze the possible mechanism of intermittent exercise in the pathologic cardiac hypertrophy of rats with myocardial infarction,study the mechanism of exercise prevention of heart failure after myocardial infarction treatment methods for providing experimental basis.Methods:48 rats were randomly divided into normal control group(group C),normal exercise group(CE group),sham operation group(S group),myocardial infarction group(MI group),myocardial infarction group(ME group),myocardial infarction +ROS Tempol group(MT group),each group of 8.The model of myocardial infarction was established by left anterior descending coronary artery ligation(LAD).S group was ligated without threading.CE group exercise for 8wk treadmill training,ME group exercise 8wk treadmill training after lwk of operation.MT group is added concentration of 2mmol/L ROS Tempol in the drinking water machine with adequate drinking water.Intermittent exercise program:1wk is adaptive training(10m/min ×30min);then the first 10m/min warm-up exercise for 10min,and then gradually increased to 25m/min x 7min and 15m/min x 3min in turn,the total time of 60min,5 days a week for 8 weeks.At the next day after exercise,the rats were anesthetized by abdominal surgery,and the hemodynamics indexes LVSP,LVEDP and ± dp/dt max were measured by retrograde introgression of the right common carotid artery.HE staining to measure the total cross-sectional area of 100 cells,Masson staining determination of collagen volume fraction(CVF).Detection of myocardium smydl gene is expressed by RT-qPCR.Western Blot was used to detect the contents of Smydl,Trxl,a-actin and BNP.T-SOD,MDA,CAT,GSH-PX kit were used to detect oxidative stress in myocardial tissue.H9C2 cardiomyocytes is cultured.Hydrogen Peroxide(H2O2)is interposed for Oxidative Stress in Non-infarcted Heart of Myocardial Infarction:(1)H9C2 cardiomyocytes were treated with different concentrations of H2O2(20?mol/L,50?mol/L,100?mol/L,200?mol/L,300 ?mol/L,500 ?mol/L,800?mol/L,1000?mol/L),and the survival rate of each treated group was detected by MTT assay at 4h,6h,12h and 24h respectively.The processing time is filtered.(2)H9C2 cardiomyocytes were treated with different concentrations of H2O2(20?mol/L,50?mol/L,100?mol/L,200?mol/L,300?mol/L).After 4 hours,the survival rate of each treatment group was detected by MTT assay.Then,protein and RNA were extracted from each group of cells.Western Blott was used to detect the protein expression levels of Smydl and Trxl in each treatment group.RT-qPCR was used to detect the gene expression level of Smydl in each treatment group.Observe the cell surface area.Results:(1)The expression of Smydl gene and protein in myocardium of non-myocardial infarction rats were significantly up-regulated.Indicating that myocardial infarction can increasingly stimulate the body Smydl gene and protein expression.(2)The cross-sectional area of myocardial cells is enlarged and the expression of Smydl is increased in myocardial infarction rats.It is speculated that Smydl can participate in compensatory hypertrophy of myocardial cells after myocardial infarction.(3)There was no significant change in Smydl gene and protein expression in normal myocardium after intermittent exercise.The results showed that Smydl had no significant effect on exercise-induced physiological cardiac hypertrophy.(4)The expression of smydl gene and protein in myocardium of myocardial infarction rats was significantly increased.After intermittent exercise can significantly reduce the non-myocardial infarction myocardial tissue smydl gene expression,while the expression of Smydl protein was not significantly decreased.(5)Myocardial infarction resulted in a significant decrease in LVSP and±dp/dtmax,LVEDP and myocardial collagen volume fraction CVF and non-myocardial infarction area significantly increased the cross-sectional area of myocardial cells.Intermittent exercise can significantly increase the heart LVSP and ±dp/dtmax,significantly reduced LVEDP and myocardial collagen volume fraction CVF and non-myocardial infarction area of myocardial cell cross-sectional area.Indicating that myocardial infarction can cause the pathological remodeling of the heart,reduce cardiac function and intermittent exercise can significantly improve the pathological remodeling of myocardial infarction heart,improve heart function.(6)Correlation analysis showed that improvement of myocardial infarction pathological remodeling and cardiac function are closely related to Smyd1 expression.(7)ROS scavenger and intermittent exercise all significantly reduced the expression of smydl gene in the heart.ROS scavenger significantly reduced the expression of smydl protein in the heart.(8)ROS scavenger and intermittent exercise significantly reduced the expression of ?-actin and BNP in the myocardial infarction heart.(9)ROS scavenger and intermittent exercise significantly decreased the expression of Trx1 protein in myocardium of myocardial infarction and significantly increased the level of T-SOD in myocardium of myocardial infarction rats,a significantly decreased the myocardial MDA content in myocardial infarction rats.Indicating that intermittent exercise generally significantly reduced the level of ROS in the myocardial infarction heart,reaching the same effect as the ROS scavenger.(10)The correlation analysis showed that the expression of Smyd1 in heart was significantly negatively correlated with SOD(P<0.01),and it was positively correlated with MDA(P<0.01).The results showed that the level of oxidative stress in cardiac hypertrophy was closely related to the expression of smydl.(11)When the concentration of H2O2 was between 50?mol/L and 200?mol/L,the expression of Trx1 protein in H9C2 cells is increased with the increment of H2O2 concentration.Indicating that H2O2 can induce the oxidative stress injury in H9C2 cardiomyocytes.(12)After 50umol/L H2O2 treatment of H9C2 cardiomyocytes 4h,the oxidative stress can upregulate Smyd1,Trx1 protein,and Smyd1 mRNA expression.It also promotes the cell hypertrophy.Indicating that Smyd1 may be involved in oxidative stress-induced cardiomyocyte histone methylation and cardiomyocyte pathology hypertrophy.It is suggesting that oxidative stress levels are closely related to Smydl.After myocardial infarction,it can reduce the level of oxidative stress,regulate Smyd1 expression and improve cardiac function.Intermittent exercise can relieve oxidative stress.Therefore,regulating the level of Trx1-Smyd1 can improve myocardial infarction myocardial infarction pathological remodeling,and the cardiac function is also improved.Conclusions:(1)The expression of Smyd1 in non-infarcted region of myocardial infarction rats was increased,and intermittent exercise could down-regulate Smyd1 expression in myocardial infarction.(2)Intermittent exercise can significantly improve the pathological remodeling of the heart of the heart,significantly improve cardiac function.Smydl expression is closely related to improvement of cardiac function.Suggesting that intermittent exercise may modulate the expression of Smydl to inhibit myocardial infarction caused by cardiac pathological remodeling and improve cardiac function.(3)Oxidative stress stimulation can up-regulate the expression of Trx1 and Smydl in cardiomyocytes,and the intermittent exercise can reduce the level of oxidative stress in the heart and the pathological remodeling of the heart.They could be achieved through the expression of Trx1-Symd1.