Inhibitory effect of aerobic exercise on left ventricular remodeling and sympathetic neural remodeling in rats with heart failure after myocardial infarction / 中国病理生理杂志

ABSTRACT

[ ABSTRACT] AIM:To investigate the effects of long-term aerobic exercise on the heart and sympathetic neural remodeling ( structure and function remodeling) in heart failure rats induced by myocardial infarction.METHODS:Heart failure model after myocardial infarction was performed by ligating anterior descending coronary artery in the Wistar rats. Four weeks after operation, the rats were randomly divided into sham operation sedentary ( S) group, heart failure sedenta-ry ( H) group and heart failure exercise ( HE) group.The animals in HE group underwent 10-week treadmill running, while those in S group and H group were sustained in a resting state.The cardiac structure and function including left ven-tricular internal diameter at diastole ( LVIDd) , left ventricular internal diameter at systole ( LVIDs) , left ventricular anteri- or wall diameter at diastole (LVAWDd), left ventricular anterior wall diameter at systole (LVAWDs), left ventricular pos-terior wall diameter at diastole ( LVPWDd) and left ventricular posterior wall diameter at systole ( LVPWDs) , and cardiac function parameters including fractional shortening (FS) and left ventricular ejection fraction (LVEF) were measured by echocardiography.The myocardium was collected for histopathological observation with Masson staining, and the collagen volume fraction ( CVF) was determined.The concentrations of norepinephrine ( NE) in the myocardium and plasma were measured by high-pressure liquid chromatography.The frequency domain analysis was applied for determining the heart rate variability (HRV) via subcutaneous recording electrode involving total power (TP), normalized low power (LFn), nor-malized high power ( HFn) and LF/HF ratio.The mRNA expression of collagen type I ( Col-I) , collagen type III ( Col-III) , atrial natriuretic factor ( ANF) ,α-myosin heavy chain (α-MHC) ,β-myosin heavy chain (β-MHC) , sarcoplasmic endoplasmic reticulum Ca2+-ATPase (SERCA2a) was detected by real-time PCR.The protein levels of nerve growth factor (NGF) and its receptor (TrkA), and tyrosine hydroxylase (TH) were measured by Western blotting.RESULTS:(1) Compared with S group, body weight ( BW) , LVIDd, FS, LVEF, TP, HFn, the mRNA expression ofα-MHC and SER-CA2a, and the protein levels of NGF, TrkA and TH decreased (P<0.05).Left ventricular weight (LVW), left ventricu-lar mass index (LVMI), LVAWDd, LVAWDs, LVPWDd, LVPWDs, CVF, plasma and myocardial NE content, LFn, LF/HF, and the mRNA expression of ANF,β-MHC, Col-I and Col-III increased ( P<0.05) in H group.(2) Compared with H group, LVW, LVMI, LVIDd, FS, LVEF, TP, HFn, the mRNA expression ofα-MHC and SERCA2a, and the pro-tein levels of NGF, TrkA and TH were raised (P<0.05), while CVF, plasma and myocardial NE content, LFn, LF/HF, and the mRNA expression of ANF, β-MHC, Col-I and Col-III decreased ( P<0.05 ) in HE group.CONCLUSION:Long-term aerobic exercise training leads to inhibition of heart and sympathetic neural remodeling and improvement of cardi-ac function and autonomic modulation in the rats after myocardial infarction.