[Certain parameters of beta-carotene metabolism in the rat].

Concentration of retinoids was decreased from 24.5 micrograms/100 ml to 13.5 micrograms/100 ml of blood serum in rats with ageing, during 2-11 months; these rats were maintained on a standard ration. Enrichment of rat ration with beta-carotene caused a statistically significant increase in content of retinoids in blood serum from 24.5 micrograms/100 ml to 48.6 micrograms/100 ml within early periods (1-72 hrs), while within later periods (0.25-2 months) the retinoid content was similar to that of control intact animals. After single and, especially, in long-term treatments with beta-carotene dose-dependent deposition of the carotenoid and increase in content of retinoids were detected in liver tissue. Use of white rats is of importance in principle for evaluation of beta-carotene caused modifications of pathological states developed under influence of unsuitable environmental factors.