The Storage Form of Vitamin A in Rat Liver Cells

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Abstract
After collagenase treatment of perfused rat liver, isolated washed hepatocytes (parenchymal cells) and washed nonparenchymal cells contained 13–53% and 5–9%, respectively, of the total vitamin A in rat liver. After Pronase E and DNase digestion of liver, nonparenchymal cells contained 1–6% of the total liver vitamin A content. By density-gradient centrifugation, hepatocytes were divided into six fractions, which contained fewer lipid globules per cell and less vitamin A per cell as the cell density increased. In our procedures, lipocytes could not be isolated after either collagenase or pronase E and DNase digestion of liver. Of the total liver vitamin A, 40–80% was found in very low density, vitamin A-containing globules, which have a median diameter of 1.7 µm (range 0.4–4.6 µm), show intense yellow-green fluorescence under UV illumination and contain >95% of their vitamin A in ester form. The distribution of vitamin A among cells and vitamin A globules in rats dosed with vitamin A was the same as in undosed rats. The possible interaction of lipocytes and different classes of hepatocytes in the storage and mobilization of vitamin A is discussed.