Hyperbaric oxygen modulates antioxidant enzyme activity in rat skeletal muscles

In skeletal muscle the activity of the enzymatic antioxidants superoxide di smutase ( OD), glutathione peroxidase (GPx) and catalase (CAT) is regulated in response to generation of reactive oxygen species (ROS). Increased acti vity of these enzymes is observed after repeated bouts of aerobic exercise. a potent stimulus for intracellular ROS production. Hyperbaric oxygen (HBO ) inhalation also stimulates intracellular ROS production although the effe cts of HBO on skeletal muscle SOD. GPx and CAT activity have not been studi ed. We tested the hypothesis that SOD, GPx and CAT activity is modulated in skeletal muscles in response to acute and repeated HBO administration. In adult male rats acute HBO inhalation (60 min at 3 atmospheres absolute) red uced catalase activity by approximately 51% in slow-twitch soleus muscles. Additionally, repeated HBO inhalation (twice daily for 28 days) increased M n2+-superoxide dismutase activity by approximately 241% in fast-twitch exte nsor digitorum longus muscles. We conclude that both acute and repeated HBO inhalation can alter enzymatic antioxidant activity in skeletal muscles.