Effects of development and ageing on pulmonary NADPH-cytochrome c reductase, glutathione peroxidase, glutathione reductase and thioredoxin reductase activities in male and female rats.

The behaviour of the principal NADPH-consuming detoxification enzymes (NADPH-cytochrome c reductase, glutathione peroxidase-glutathione reductase system, and thioredoxin reductase) was studied during development and senescence of the rat lung. We have also studied the influence of sex on the development and senescent values. The NADPH-cytochrome c reductase activity increases at birth and afterwards remains constant until the 25th day after birth, at which age there is a maximum activity. Its activity decreases during the ageing period in both sexes. The glutathione reductase and thioredoxin reductase activities show significant differences with respect to sex during the adult stage, however during ageing these differences disappear. These enzymes show maximum activity at 25 days after birth, and afterwards the activity decreases continuously until the adult levels are reached. The activity of glutathione reductase is increased during the ageing period, especially in the female rats, however, in senescence the levels of thioredoxin reductase are lower than in the adult stage. The glutathione peroxidase shows a significant difference between both sexes during senescence and in the male its activity in this stage is higher than during development and adulthood.