The effects of moderate intensity exercise on left ventricular remodeling in spontaneously hypertensive rats / 中华物理医学与康复杂志

ABSTRACT

Objective:To observe any effect of moderate-intensity exercise on left ventricular remodeling (such as cardiomyocyte hypertrophy, apoptosis and proliferation) in spontaneously-hypertensive rats (SHRs) and explore the possible mechanisms.Methods:Thirty 4-month-old female SHRs were randomly divided into a sedentary group ( n=15) and an exercise group ( n=15). Fifteen Wistar Kyoto rats served as the control group. The exercise group underwent daily 60-min moderate-intensity treadmill exercise 5 days per week for 12 weeks, while the sedentary and control groups were raised quietly in cages for the same period. After the 12-week intervention, the caudal artery blood pressure was measured using a non-invasive blood pressure monitor. The rats were then sacrificed and their hearts were sampled for morphometric measurement. Cardiomyocytes were isolated and underwent DAPI staining to measure their length, width and area. Apoptosis cardiomyocytes was detected by using terminal-deoxynucleoitidyl transferase mediated nick end labeling and their proliferation was assessed using immunofluorescent staining. The number of cardiac progenitor cells was detected by flow cytometry, while the expression of the cardiac calcineurin Aβ subunit (CNAβ) and phosphorylated Akt (p-Akt) protein were measured using western blotting. Results:Compared with the control group, a significant increase was observed in the heart weight, heart mass index (HMI), systolic blood pressure, diastolic blood pressure, myocardial thickness of the left ventricular wall (anterior wall, posterior wall and septal wall), cardiomyocyte morphology (length, width and area), cardiomyocyte apoptosis rate, proliferation rate, number of cardiac progenitor cells and protein expression of CNAβ in the sedentary group. Compared with the sedentary group, the average heart weight, HMI, myocardial thickness of the left ventricular wall (anterior wall, posterior wall and septal wall), cardiomyocyte morphology (length, width and area), cardiomyocyte proliferation rate, number of cardiac progenitor cells and p-Akt protein expression had increased significantly in the exercise group. The average systolic blood pressure, diastolic blood pressure, apoptosis rate and CNAβ protein expression had decreased significantly.Conclusions:Moderate-intensity exercise can induce physiological cardiac hypertrophy in SHRs, relieve apoptosis, increase the number of cardiac progenitor cells and promote cell proliferation, thereby inhibiting cardiac remodeling.