[Comparison of the activities of the hepatic and renal mixed function oxidase (MFO) systems in rats during different postnatal periods of life].

In an effort to investigate the diminished capacity of young and old individuals to metabolize certain drugs--in this paper--the effect of different age on the concentrations of the hepatic and renal mixed function oxidase systems of rats was studied. Microsomal cytochrome P-450 concentration and NADH-cytochrome b5 reductase activity were increased both in liver (to 1-2 months) and in kidney (to 2-4 months), and then were decreased. Aging not changed concentrations of hepatic and renal cytochrome b5 after 2 months of life. NADPH-cytochrome P-450 reductase activities were decreased in both organs of young rats and were increased in old rats livers and decreased in old rats kidneys.