Effects of aging on hepatic and pulmonary glutathione S-transferase activities in male and female Fischer 344 rats.

The effects of aging on cytosolic glutathione S-transferase activities were evaluated with liver and lung cytosol from male and female Fischer 344 rats 3, 12, and 24 months of age. Age-related changes were tissue-, sex-, and substrate-specific. With liver and lung cytosol from both males and females, rates of metabolism of 1,2-epoxy-3-(p-nitrophenoxy)propane and p-nitrobenzyl chloride were lower in the old group than in the young group; however, patterns of decrease differed with tissue and sex. With 1,2-dichloro-4-nitrobenzene, metabolism was affected by aging only in liver and lung cytosol from males. Finally, with 1-chloro-2,4-dinitrobenzene, metabolic rates were altered during aging only with liver cytosol from females. However, the apparent Km was higher with liver cytosol from old males; those values from lung cytosol of males and liver or lung cytosol from females were unchanged. These data indicate that changes in the cytosolic glutathione S-transferase isozymes occurred during aging.