Studies on Metabolism of Vitamin A. 3. The Mode of Absorption of Vitamin a Esters in the Living Rat

Abstract

In the preceding paper (Mahadevan, Seshadri Sastry & Ganguly, 1963) experiments with living animals have shown that vitamin A esters are hydrolysed and resynthesized during absorption. In this paper, where experiments conducted in vitro with everted intestinal sacs of rats are described, further evidence is produced to show that prior hydrolysis of vitamin A esters is essential for the

Development of Vitamin a-Rich Lipid Droplets in Multivesicular Bodies of Rat Liver Stellate Cells

“…The present observations are consistent with the view expressed in biochemical reports (Mahadevan and Ganguly, 1961;Mahadevan et al, 1963;Futterman and Andrews, 1964). The biochemical data on vitamin A uptake in the liver, obtained using fractions from the organ homogenate, seem to indicate that this uptake is a function of the stellate cells, because vitamin A in the liver is mainly stored in the lipid droplets of the stellate cells (Nakane, 1963;Wake, 1964Wake, , 1971Hirosawa and Yamada, 1973).…”

The intestinal absorption and metabolism of vitamin A and beta-carotene in man.

“…Furthermore, it has been pointed out (7) that, in the rat, the composition of the fatty acids attached to the a' position of lymph lecithin strongly resembles the fatty acid composition of newly absorbed lymph retinyl esters. Table V summarizes the composition of the fatty 5 Although small amounts of radioactivity (5 to 1% of the total retinyl ester radioactivity) were consistently found at or just above the origin (below the linoleate zone) after thin layer chromatography, this radioactivity apparently resided in oxidation products formed during chromatography. Thus, after elution from the thin layer plate and rechromatography on an alumina column, less than 10% of this radioactivity was recovered in the retinyl ester fraction (column fraction 2).…”

Fat-Soluble Vitamins

“…In continuation of studies on the mechanism of vitamin A absorption, Ganguly et al (33), experimenting in vivo with rats, present new evid�nce that hydrolysis of vitamin A esters is essential for absorption, regardless of whether oily solutions (lr aqueous dispersions were administered. In various tissues, like intestine (mucosa and muscles), blood, and liver, vitamin A alcohol was found independent of the type of the ester administered.…”