The fate of intracardially administered retinyl esters in the rat.

Irrespective of the form of vitamin A fed to rats, it appears in blood almost exclusively as retinyl palmitate, and the liver always stores only this ester. Differences in the fatty acid composition of the dietary fats do not seem to have any influence on the type of retinyl ester absorbed and stored by the rat (Mahadevan & Ganguly, 1961; Mahadevan, Seshadri Sastry & Ganguly, 1963). It was therefore suggested that probably some specific lipoprotein transports retinyl palmitate from the intestine and stores it in the liver of rats (Mahadevan & Ganguly, 1961). If this were so, the intracardial injection of different retinyl esters into rats should lead to ready deposition in the liver of the palmitate in preference to the other esters. It is shown in the present paper that, when different retinyl esters are injected, the palmitate is more readily taken up by the liver, whereas, although small amounts of the other injected esters can be found in this tissue shortly after the injection, in the course of time they are all stored as the palmitate.