Effects Of Exercise Traning On Ventricular Remodeling Following Myocardial Infarction In Rats

Objective: To assess the effects of different initiation time of exersice training on ventricular remodeling,and to explore the effects of exercise training on the level of ST2,IL-33 hs-CRP and NT-pro BNP and cardiac function after acute myocardial infarction in rats.Moreover,its possible mechanism is investigated simultaneously.Methods: Healthy male wistar rats(7-8 weeks old)underwent surgically induced MI.After surgery,rats were randomly assigned into two major groups,based on the designated starting time of exericise training.Exercise groups started exercise at either 1 week(1W-Group)or 4 week(4W-Group)after MI and exercised on a treadmill for 8 weeks.Group starting exercise 1 or 4 week after MI included sham-operated control group(1W-Sham,n=8/4W-Sham,n=8),sedentary group(1W-Sed,n=10/4W-Sed,n=10),and exercise training group(1W-ET,n=10/4W-ET,n=10).Echocardiograhpy was performed after exercise protocol.Blood samples were obtained at 48 hours after the last exercise,at which point the hearts were also harvested for histological and molecular analysis.The histological changes of myocardial tissue were observed by HE and Masson staining.The protein levels of ST2 and IL-33 in infarct border zone were detected by Western Blot,and the m RNA expression were examined by real-time PCR.Result: Compared with sedentary group(1W-Sed group and 4W-Sed group included),the percentage of CVF reduced(P < 0.01);LVEF,FS increased(P<0.05),LVEDD decreased(P<0.05);the concentration of serum ST2,NT-pro BNP and hs-CRP decreased(P<0.05);the level of serum IL-33 was no statistic significance;the expression of ST2 protein and m RNA decreased in infarct border zone(P<0.05);the expression of IL-33 protein and m RNA in infarct border zone was no statistic significanc in exersice group(1W-ET group and 4W-ET group included)after the exercise protocol.The level of serum ST2 was positively correlated with NT-pro BNP(r=0.577,P< 0.01),and negatively correlated with LVEF after the exercise protocol(r=-0.523,P<0.01).There was no statistic significance between 1W-ET group and 4W-ET group in each index.Conclusion: Early exercise training may attenuate myocardial fibrosis,improve ventricular remodeling and preserve cardiac function after myocardial infarction.Exercise starting 1 or 4 week after myocardial infarction affects ventricular remodeling and cardiac function similary,suggesting that early exercise training is safe and effective.Exercise training may enhance IL-33/ST2 signaling pathway during ventricular remodeling after AMI.