Nutritional, cardiac and adrenergic changes induced by swimming training in rats
Moreau, D.; Guilland, J.C.; Noirot, P.; Malval, M.
Journal de Physiologie 75(7): 755-764
1979
ISSN/ISBN: 0021-7948 PMID: 547071 Document Number: 150951
The effects of training were investigated in male Sprague Dawley rats group (N), fed ad lib, by measuring the weight increase and food intake of the animals, biochemical parameters (myocardial triglycerides and glycogen levels), mechanical and metabolic properties of the heart and adrenergic reactions to swimming stress. Another group of rats remaining sedentary served as control (T). Conditioned rats had been submitted to a 1 h test swim 6 days a wk for 9 wk. Gradually additional weights were fixed to the thorax. At the end of training, the load reached 6% of the body weight. Both groups were sacrificed by decapitation at the same time, 30 h after the last swimming session. The study of mechanical performances and metabolic properties was achieved with isolated working heart preparation. Adrenergic reactions of swimming stress were evaluated from plasma, heart and adrenal catecholamine concentrations. The swimming program induced a reduced rate of weight increase and food intake. Conditioned rats showed an elevated heart/body weight ratio. Though food intake was reduced, myocardial glycogen and triglyceride contents were increased, but heart catecholamine concentration was not significantly altered. Chronic training improved myocardial mechanical performances: aortic and coronary flows, cardiac output, dP/dt ratio and left ventricular pressure were increased in isolated working conditioned heart preparations. O2 consumption and pressure work were greater than in the control group, but cardiac efficiency was not significantly different between the 2 groups. The intrinsic conditioned heart rate was lower than in the control hearts. Endogenous triglycerides and exogenous free fatty acid utilization rates were increased in trained perfused hearts. The swimming training program produced a severe chronic stress shown by a strong overstimulation of sympathico-adrenal system.