Effects of dietary antioxidant supplementation on oxidative damage and resistance to oxidative damage during prolonged exercise in sled dogs

Objectives - To determine effects of dietary antioxidant supplementation on plasma concentrations of antioxidants, exercise-induced oxidative damage, and resistance to oxidative damage during exercise in Alaskan sled dogs. Animals - 62 Alaskan sled dogs. Procedure - Dogs were matched for age, sex, and ability and assigned to 1 o f 3 groups: sedentary and nonsupplemented (control [C]; n = 21), exercised and supplemented (S; 22), and exercised and nonsupplemented (N; 19). Dogs i n group S were given 400 units of alpha-tocopherol acetate, 3 mg of beta-ca rotene, and 20 mg of lutein orally per day for 1 month, then dogs in groups S and N completed 3 days of exercise. Blood samples were collected before and after 1 and 3 days of exercise and after 3 days of rest. Plasma antioxi dant concentrations were determined, and oxidative damage to DNA (plasma 7, 8 dihydro-8-oxo-2'deoxyguanosine [8-oxodG] concentration) and membrane lipi ds (plasma hydroperoxide concentration) and resistance of plasma lipoprotei ns to oxidation were assessed. Results - Supplementation increased plasma concentrations of alpha-tocopher ol, beta-carotene, and lutein. Plasma concentration of alpha-tocopherol inc reased and concentration of lutein decreased in group S with exercise. Conc entration of 8-oxodG decreased in group S but increased in group N during a nd after exercise. Lag time of in vitro oxidation of lipoprotein particles increased with exercise in group S only. Conclusions and Clinical Relevance - Dietary supplementation with antioxida nts resulted in increased plasma concentrations of antioxidants. Moreover, supplementation decreased DNA oxidation and increased resistance of lipopro tein particles to in vitro oxidation, Antioxidant supplementation of sled d ogs may attenuate exercise-induced oxidative damage.