Studies on the absorption,deposition and depletion of vitamin A in the rat

Vitamin A-deficient albino rats were fed orally approximately 100 μg. of vitamin A dissolved in cottonseed oil, and at various time intervals rats were sacrificed, and livers, kidneys, and in some instances plasma were analyzed for vitamin A present.A plasma value of approximately 18–30 μg. % of vitamin A was maintained before liver storage occurred, indicating that physiological needs must be satisfied before vitamin A is deposited in the liver.Vitamin A first appeared in the blood, then in the liver, and finally in the kidneys, and data presented suggest that kidney vitamin A originates from previously deposited hepatic vitamin A.During depletion the hepatic and kidney vitamin A converged until the liver to kidney total vitamin A ratio approached unity. Plasma vitamin A remained relatively constant at approximately 30 μg. % during depletion and during rapid loss of hepatic vitamin A storage. Kidney vitamin A showed no substantial decrease during this period. A linear relationship was found between liver and kidney vitamin A when the body reserves were being exhausted. These observations suggest that, at least during the latter stages of depletion, the vitamin A in the kidneys may be important in meeting the physiological needs of the rat.