Data/hora: 01/06/2024 02:17:06

Provedor de dados: 	56	
País: 	Brazil	
Título: 	Swimming training increases cardiac vagal activity and induces cardiac hypertrophy in rats	
Autores: 	Medeiros,A.; Oliveira,E.M.; Gianolla,R.; Casarini,D.E.; Negrão,C.E.; Brum,P.C.	
Data: 	2004-12-01	
Ano: 	2004	
Palavras-chave: 	Swimming-training exercise; Cardiac autonomic balance; Hemodynamics; Hypertrophic effect; Parasympathetic system; Resting bradycardia.	
Resumo: 	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.	
Tipo: 	Info:eu-repo/semantics/article	
Idioma: 	Inglês	
Identificador: 	http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2004001200018	
Editor: 	Associação Brasileira de Divulgação Científica	
Relação: 	10.1590/S0100-879X2004001200018	
Formato: 	text/html	
Fonte: 	Brazilian Journal of Medical and Biological Research  v.37 n.12 2004	
Fonte: 	info:eu-repo/semantics/openAccess