Please use this identifier to cite or link to this item: https://repositorio.unifesp.br/handle/11600/2322
Title: Swimming training increases cardiac vagal activity and induces cardiac hypertrophy in rats
Authors: Medeiros, Alessandra [UNIFESP]
Oliveira, Edilamar Menezes de
Gianolla, R.
Casarini, Dulce Elena [UNIFESP]
Negrão, C.e.
Brum, Patricia Chakur
Universidade de São Paulo (USP)
Universidade Federal de São Paulo (UNIFESP)
Keywords: Swimming-training exercise
Cardiac autonomic balance
Hemodynamics
Hypertrophic effect
Parasympathetic system
Resting bradycardia
Issue Date: 1-Dec-2004
Publisher: Associação Brasileira de Divulgação Científica
Citation: Brazilian Journal of Medical and Biological Research. Associação Brasileira de Divulgação Científica, v. 37, n. 12, p. 1909-1917, 2004.
Abstract: The effect of swimming training (ST) on vagal and sympathetic cardiac effects was investigated in sedentary (S, N = 12) and trained (T, N = 12) male Wistar rats (200-220 g). ST consisted of 60-min swimming sessions 5 days/week for 8 weeks, with a 5% body weight load attached to the tail. The effect of the autonomic nervous system in generating training-induced resting bradycardia (RB) was examined indirectly after cardiac muscarinic and adrenergic receptor blockade. Cardiac hypertrophy was evaluated by cardiac weight and myocyte morphometry. Plasma catecholamine concentrations and citrate synthase activity in soleus muscle were also determined in both groups. Resting heart rate was significantly reduced in T rats (355 ± 16 vs 330 ± 20 bpm). RB was associated with a significantly increased cardiac vagal effect in T rats (103 ± 25 vs 158 ± 40 bpm), since the sympathetic cardiac effect and intrinsic heart rate were similar for the two groups. Likewise, no significant difference was observed for plasma catecholamine concentrations between S and T rats. In T rats, left ventricle weight (13%) and myocyte dimension (21%) were significantly increased, suggesting cardiac hypertrophy. Skeletal muscle citrate synthase activity was significantly increased by 52% in T rats, indicating endurance conditioning. These data suggest that RB induced by ST is mainly mediated parasympathetically and differs from other training modes, like running, that seems to mainly decrease intrinsic heart rate in rats. The increased cardiac vagal activity associated with ST is of clinical relevance, since both are related to increased life expectancy and prevention of cardiac events.
URI: http://repositorio.unifesp.br/handle/11600/2322
ISSN: 0100-879X
Other Identifiers: http://dx.doi.org/10.1590/S0100-879X2004001200018
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