title: Liver takes up retinol-binding protein from plasma.
abstract: Retinol is transported in plasma bound to a specific transport protein, retinol-binding protein. We prepared 125I-tyramine cellobiose-labeled rat retinol-binding protein and studied its tissue uptake 1, 5, and 24 h after intravenous injection into rats. The liver was the organ containing most radioactivity at all time points studied. After 5 and 24 h, 30 and 22% of the injected dose were recovered in liver, respectively. After separating the liver into parenchymal and nonparenchymal cells in the 5-h group, we found that both cell fractions contained approximately the same amount of radioactivity (per gram of liver). Most of the retinol-binding protein radioactivity in the nonparenchymal cell fraction was in the stellate cells. The implication of these results for a possible transfer mechanism for retinol between parenchymal and stellate cells is discussed.
mesh_terms: D000818:Animals; D002469:Cell Separation; D002475:Cellobiose; D004727:Endothelium / Q000378:metabolism; D006801:Humans; D007457:Iodine Radioisotopes; D007668:Kidney / Q000378:metabolism; D007700:Kinetics; D007728:Kupffer Cells / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D012177:Retinol-Binding Proteins / Q000378:metabolism*; D054839:Retinol-Binding Proteins, Plasma; D014018:Tissue Distribution; D014439:Tyramine; D014801:Vitamin A / Q000097:blood* / Q000378:metabolism; D014802:Vitamin A Deficiency / Q000378:metabolism
chemical_list: D007457:Iodine Radioisotopes; D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma; C038394:tyramine-cellobiose adduct; D014801:Vitamin A; D002475:Cellobiose; D014439:Tyramine