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.