Resumo

BOFFI, FM et al. DNA damage induced by exercise in middle gluteal muscle of thoroughbreds horses. BAG, J. basic appl. genet. [online]. 2007, vol.18, n.2, pp.1-10. ISSN 1852-6233.

It is well known that two classical consequences of severe exercise are soreness and stiffness. Both consequences develop in the days following severe exercise. The objective of the present work was to establish the association between DNA damage, the energetic metabolism and the effects of the generation of oxygen free radicals in middle gluteal muscle of horses, measured after a severe exercise bout on a treadmill. Four thoroughbreds, ranging in aged from 3 to 4 years old were used for this study. The test consisted in warming-up, severe exercise, and cooling down. Venous blood samples were withdrawn via a catheter from the jugular vein before and at 5 min, 30 min, 45 min and 24 h post-exercise. Muscle biopsy samples were obtained from the middle gluteal muscle before and at 45 min and 24 h after exercise. All statistical analyses were performed using Student's t-tests for unpaired data. ATP concentration significantly decreased (p< .05) after 45 min of severe exercise and subsequently increased by 24 h. Plasma CK activity increased significantly (p< .05) after 45 min and 24 h of exercise. Both free MDA and protein-bound MDA concentrations significantly increased (p< .001) after 45 min of exercise, and both of them returned almost to the pre-exercise values after 24 h of exercise. The percentage of TUNEL positive cells increased significantly (p< .001) so as the plasma hypoxanthine and uric acid level during exercise. It was strongly suggested that the generation of free radicals was developed during exercise. The mechanism of exercise-induced myopathy could be the cell membrane damage by lipid peroxidation and DNA fragmentation in the working muscle cells by free radicals generation.

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