The cellular distribution of vitamin A in the liver

Hepatic vitamin A (VA) is concentrated in lipocytes (fat-storing cells) but the actual concentration in various cell types has not been measured. In this study hepatocytes from normal and VA-pre-treated rats were isolated and the VA content was measured. Because most lipocytes were lysed in the procedure, VA content within lipocytes was estimated indirectly by subtracting total hepatic VA from hepatocellular VA. Hepatocytes contained 10.9% of the total hepatic VA (7.2% in VA-treated rats). The volume density of lipocytes in whole liver was 0.23% as determined morphometrically (1.45% in VA-treated rats). From these results it is estimated that the VA concentration in lipocytes is 39 mg/ml (3015 times that in hepatocytes) in normal rats and 69 mg/ml in VA-treated rats. Lipocyte lipid droplets are estimated to be 26% retinyl palmitate (by volume) in normal rats and 31% in VA-treated rats.