The storage form of vitamin A in rat liver cells

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 microns (range 0.4-4.6 microns), show intense yellow-green fluorescence under UV illumination and contain greater than 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.