Effects of acute exercise on lung antioxidant enzymes in young and old rats.

The lung could be the target organ to cellular damage, since it is directly exposed to high concentrations of oxygen. Acute exercise and age would be an added challenge to the lung, and therefore, we investigated alterations of major lung antioxidant enzymes (manganese-superoxide dismutase, Mn-SOD; copper-zinc-SOD, Cu-Zn-SOD; glutathione peroxidase, GPX; catalase, CAT) activities and mRNA expressions in young (4 months old) and old (26 months old) male Wistar rats with exercise. Thioredoxin reductase (TrxR) activity was also investigated. Mn-SOD and Cu-Zn-SOD increased with age, but age did not affect GPX, CAT, or TrxR activity. Acute exercise in young animals increased the activities of Mn-SOD, Cu-Zn-SOD, and CAT. In contrast, only Mn-SOD increased significantly in the old animals. The mRNA expressions of Mn-SOD, Cu-Zn-SOD and GPX were not altered with age, while CAT mRNA expression decreased with age. Acute exercise had no significant effect on any of the antioxidant enzyme mRNA expression. Moreover, reactive carbonyl derivative increased with age, but no significant changes were detected after acute exercise in either group. In summary, antioxidant enzymes responsible for the removal of hydrogen peroxide were unable to increase their enzyme activities in the old animals with exercise.