STUDIES ON METABOLISM OF VITAMIN A. 4. STUDIES ON THE MODE OF ABSORPTION OF VITAMIN A BY RAT INTESTINE IN VITRO

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Abstract
After incubation of everted intestinal sacs prepared from normal male rats, in media containing aqueous dispersions of vitamin A alcohol or its various esters, the particulate and supernatant fractions of the mucosal-cell homogenates were analysed. Although there was no significant esterification of vitamin A alcohol, considerable hydrolysis of all the esters occurred in the medium. In all cases the particulate materials contained the bulk of the vitamin A as alcohol, whereas the ester predominated in the supernatant, where it was mostly in the form of vitamin A palmitate. The effect of inhibitors and activators of the enzymes hydrolysing and synthesizing vitamin A esters was studied. The results are discussed in relation to the possible situation of the enzymes in the cell.