STUDIES ON METABOLISM OF VITAMIN A. 3. THE MODE OF ABSORPTION OF VITAMIN A ESTERS IN THE LIVING RAT

Abstract

After starvation for 24 hours rats were fed with vitamin A alcohol or its various esters in groundnut oil or as aqueous dispersions in Tween 20, and the free alcohol and the esters were analysed in the tissues of the intestinal tract, blood and liver 3 hours after the dose. Regardless of the ester fed, there was considerable vitamin A alcohol in all tissues analysed, but the palmitate predominated in the intestinal mucosa and was almost the only ester in the other tissues. The particulate materials of the mucosal-cell homogenate contained the bulk of the vitamin A alcohol of the cells, whereas the supernatant had the major portion of the ester, which was mostly as the palmitate, with traces of the fed ester. It is suggested that all esters of vitamin A are hydrolysed, whereupon the vitamin A alcohol crosses the cell membrane and is re-esterified, preferentially with palmitic acid, inside the cell.