[On the potential protective properties of vitamin A in carcinogenesis]

The effect of massive doses of vitamin A was studied as applied to the tumor growth in rats with Guerin's carcinoma, protein biosynthesis in them and enzymic activity. It is established that intraperitoneal administration of vitamin A massive doses (the total quantity being 4000 000 and 2000 000 I.U.) in equal doses for 6 days decreases tumor sizes and weight, intensity of protein biosynthesis by the cell-free protein-synthetizing system of the small intestine mucosa, intensifies activity of retinylpalmitate hydrolase, decreases that of retinylpalmitate synthetase, increases the activity of alanine aminotransferase. The authors assume that under the effect of vitamin A massive doses the capacity of retinol-binding protein transporting vitamin A is exhausted, the latter being transported in a cell by lipoproteids, which causes the cell membrane lysis.