Effects of xanthine oxidase inhibition on oxidative stress and swimming performance in rats

The aim of this study was to examine the effect of allopurinol, a xanthine oxidase inhibitor, on oxidative stress and physical performance after swimming until exhaustion in rats. Blood and gastrocnemius muscle samples were collected before, immediately after, and 5 h after exercise and the respective timepoints after allopurinol administration. Xanthine oxidase and total antioxidant capacity (TAC) were determined in plasma and muscle, whereas catalase activity and reduced (GSH) and oxidized (GSSG) glutathione were measured in erythrocytes and muscle. Thiobarbituric acid–reactive substances (TBARS) and protein carbonyls (PC) were determined in plasma, erythrocytes, and muscle. As expected, allopurinol inhibited xanthine oxidase activity. Compared with their nonallopurinol-treated counterparts, rats treated with allopurinol showed a 35% decrease in physical performance, as indicated by the shorter swimming time to exhaustion. Exercise alone increased PC and TBARS concentration in plasma, erythrocytes, and ...