Studies on metabolism of vitamin A. 1. The biological activity of vitamin A acid in rats

Abstract

Vitamin A acid was biologically 48.9% as active as all-trans-vitamin A acetate in rats when given orally, and 141% as active when injected intraperitoneally. When vitamin-A-deficient rats were fed with 10 [mu]g of vitamin A acid or the acetate/day, the acid-fed rats showed a more pronounced growth response within 24 hr. of the dose, drank considerably more water and excreted less urine than the acetate-fed group. A single dose of 500 [mu]g. of the acid could sustain the growth rate of vitamin-A-deficient rats for 4 weeks. The implications of these results are discussed and it is suggested that the marked growth in response to vitamin A acid may be due to a more rapid correction of water imbalance in the deficient animals.