Age-related changes in the antioxidant screen of the distal lung in mice.

We studied the influence of age on glutathione (GSH) content in the distal lung and the lung tissue of mice. From 1 to 28 months of age, the quantity of GSH and glutathione disulfide (GSSG) in bronchoalveolar lavage (BAL) fluid and in the lung tissue were determined. The GSH content in BAL fluid, which reflects the antioxidant screen of the distal lung, decreased with advancing age. The ratio of GSSG to GSH increased in later life, suggesting increase of oxidation of the epithelial lining fluid in old mice. The GSH content in the lung tissue also decreased with aging. Therefore the lower respiratory tract may be less able to defend against external attack, including attack by oxygen-derived active molecules, in senescent mice. The decrease of the antioxidant screen of the distal lung may be associated with impaired lung defense in relation to oxidant-antioxidant balance in aged mice.