Abstract 421: Cardiac Hypertrophy Induced by Swimming Exercise in Mice and the Cardiac Renin-Angiotensin System: The More, the Better?

Autor: Santiago Alonso L Tobar, Douglas S Soares, Graziela H Pinto, Daniel S Caetano, Amanda Lopes, Michael E Andrades, Nadine O Clausell, Luis Eduardo P Rohde, Andréia Biolo
Rok vydání: 2017
Předmět:
Zdroj: Circulation Research. 121
ISSN: 1524-4571
0009-7330
Popis: Cardiac hypertrophy is an adaptive process which is triggered by different mechanism in order to improve blood flow to organism and it may progress as physiological or pathological. Physical exercise offers a wide range hemodynamic stimulus; consequently it may modulate several molecular mechanisms associated to cardiac hypertrophy, for instance the local cardiac renin-angiotensin system (RAS). Thus, the aim of this study was to analyze the classical (ANGII/AT1) and alternative (ANG1-7/MAS) axis of the RAS in the cardiac muscle of mice submitted to exercise with different volumes/intensity training for the development of cardiac hypertrophy. Therefore, male Balb/c mice were divided in three groups: (i) Sedentary (SED), (ii) swimming training twice a day (T2), and (iii) swimming training three times a day with 2% of body weight overload (T3), for six weeks of training. The cardiac hypertrophy was assessed by the left ventricle weight and tibial length (LV/mm) ratio and cardiomyocytes cross-sectional area. Angiotensin peptides were analyzed by HPLC and angiotensin receptor measured by western blotting. We have also analyzed fibrosis by masson’s tricrome and the fetal genes reactivation was assessed by qRT-PCR. Both swimming training induced cardiac hypertrophy, the CHI for groups was T2 (6.34±0.44 mg/mm) and T3 (6.74 ± 0.70 mg/mm) compared to SED (5.55±0.5 mg/mm, p = 0.002). There was no observed change in the levels of angiotensin peptides ANG-I, ANG-II, and ANG1-7 between training groups and sedentary, however when we analyze angiotensin receptors, group T3 showed higher levels of AT1 when compared to SED (p=0.004), while MASR levels was higher in T2 compared to SED (0.017). Further, there was moderate reactivation of fetal genes as evidenced by increased in MHC-β expression observed in T3, but without fibrosis in either group. Our results suggest that increasing volumes/intensity of exercise beyond moderate does not influence the magnitude or the structural phenotype of physiological cardiac hypertrophy. However, it might promote the activation of molecular mechanisms involved in pathological cardiac hypertrophy.
Databáze: OpenAIRE