Biliary excretion of polystyrene microspheres depends on the type of receptor-mediated uptake in rat liver.
Hepatic uptake and biliary excretion of fluorescein isothiocyanate-labeled polystyrene microspheres with a particle size of 50 nm (MS-50) were studied in rats. Liver perfusion studies revealed that not only apo-E-mediated but also asialoglycoprotein receptor-mediated uptake is involved in the mechanism of the serum protein-dependent uptake of MS-50 in the liver. The uptake of MS-50 mediated by apo-E contributes more to the total uptake of MS-50 by the hepatocytes than that via asialoglycoprotein receptor in the presence of serum in the perfusate. Furthermore, it was found that MS-50 is substantially excreted into the bile by transcytosis. The extent of exocytosis of MS-50 taken up by the hepatocytes was much higher after MS-50 was endocytosed via asialoglycoprotein receptor than after taken up via the process mediated by apo-E. On the basis of these results, a possible regulation of the intracellular sorting of ligands, depending on the receptor-mediated uptake mechanism, was inferred.
Furumoto
K
K
Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan.
Ogawara
K
K
Yoshida
M
M
Takakura
Y
Y
Hashida
M
M
Higaki
K
K
Kimura
T
T
D000818:Animals; D037263:Asialoglycoprotein Receptor; D001646:Bile / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D008863:Microspheres; D010477:Perfusion; D011137:Polystyrenes / Q000032:analysis / Q000097:blood / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000378:metabolism*
D037263:Asialoglycoprotein Receptor; D011137:Polystyrenes; D011956:Receptors, Cell Surface