Four major questions are posed: 1) What are the relative roles of lipocytes, "light" hepatocytes and "heavy" hepatocytes in the storage and mobilization of vitamin A in the liver? 2) What are the biochemical, metabolic and structural characteristics of the vitamin A-containing globules of lipocytes and "light" hepatocytes? 3) What is the nature of the intercellular transfer agent that transports vitamin A between lipocytes and hepatocytes? 4) How do extraneous factors, such as ethanol ingestion, protein malnutrition and the intake of carbon tetrachloride, influence the storage and mobilization of vitamin A in the liver? In regard to the first question, the uptake of chylomicra (CM) and chylomicron remnants (CMR) labeled with 3H-retinyl ester by cell types of the liver in vivo, by cells of the isolated perfused liver and by isolated liver cell types, will be studied as a function of vitamin A status. Relative to the second question, the chemical composition of vitamin A-containing globules (VAG) isolated from lipocytes and from "light" hepatocytes will be determined, the possible association of retinyl ester synthase and retinyl ester hydrolase with VAG will be explored, and the ultra structure of VAG, both in intact liver and in the isolated state, will be studied. The nature of the intercellular transfer of vitamin A will be explored by attempting to isolate an interstitial retinol binding protein from liver cell preparations, by following the uptake and release of labeled retinol by isolated liver cells, and by examining direct intercellular transfer mechanisms. The influence of acute ethanol toxicity, protein malnutrition and CC14 toxicity on the capability of liver cells to take up and release labeled retinol both in vivo and in vitro will be measured. Ultrastructural studies of liver morphology will also be conducted.