Lipid peroxidation in exercise myopathy.

Selected estimates of lipid peroxidation were analyzed in mouse quadriceps femoris muscle immediately after submaximal prolonged (9 hr) and exhaustive maximal running (2-3 hr), and at intervals 1-10 days afterward during the exercise-induced myopathy. Immediately after the two types of exertion no significant changes were observed in the concentrations of lipid peroxidation products (thiobarbituric acid (TBA) reactive substances, and lipofuscin) or in the estimates of autoxidation (spontaneous and Fe2+-induced autoxidations) and antioxidant (catalase, glutathione peroxidase, and vitamin E) capacities. The enzymatic estimate of exercise myopathy (beta-glucuronidase) increased considerably (2-6 days) after both types of exertion. Simultaneously, the lipid peroxidation rate of muscle homogenates in vitro increased markedly and in highly significant correlation with the activity of beta-glucuronidase. The concentrations of TBA reactants and lipofuscin as well as Fe2+-induced lipid peroxidation were not affected during exercise myopathy. The activities of catalase and glutathione peroxidase increased significantly after both exertions, while the concentration of vitamin E was unchanged. Exhaustive running of endurance-trained mice caused only slight signs of myopathy and no increase in the rate of lipid peroxidation in vitro.