[Role of vitamin A in chemical carcinogenesis in the mammary gland].

The effect of feeding rats with high doses of vitamin A on the distribution of polycyclic hydrocarbon, 7,12-dimethylbenzanthracene (DMBA) and its metabolites in different organs and blood, and also on the metabolic rate in the liver was studied following intravenous injection of the carcinogen. Hypervitaminosis A resulted in a significant decrease of the level of DMBA and its metabolites in all the organs investigated and in the blood. The rate of DMBA metabolism in the liver of the animals rose with the increase of the vitamin A dose.

[Change in the metabolism of 7,12-dimethylbenz(a)anthracene under the influence of vitamin A].

The in vitro metabolism of 7,12-dimethylbenz(a)anthracene in its incubation with the liver microsomes, the liver and mammary gland homogenates of rats, kept on vitamin A-enriched diet, was studied. Vitamin A inhibited the formation of lipophilic metabolites and increased the generation of water-soluble metabolites. The amount of lipophilic metabolites extracted from the microsomes and the liver and mammary gland homogenates were decreased by a factor of 2.