[The microsomal oxidation system of the liver in the aging of animals with various specific lifespans].

Experiments, carried out on adult and old animals with different specific lifespan (rat, guinea pig, rabbit, and dog), revealed age-related changes in content and activity of liver microsomal oxidation enzymes (cytochrome P-450, b5, aminopyrine demethylase, aniline hydroxylase). The changes become more pronounced with age. This allows to classify these species as chronobiological ones. A negative correlation between the specific lifespan and the level of decrease in activity of aminopyridine demethylase, an integral index of electron transport rate in microsomal chain, in aged animals was established.