Uptake of [(3)H]bilirubin in freshly isolated rat hepatocytes: role of free bilirubin concentration.
Hepatocytic transport of physiological concentrations of unconjugated bilirubin (UCB) has not been determined in isolated liver cells. Initial uptake of highly purified [(3)H]UCB was measured in rat hepatocytes in the presence of human serum albumin at various free, unbound UCB concentrations, [UCB]. At [UCB]=42 nM (below aqueous solubility of 70 nM), uptake was strictly temperature dependent; this was much less evident at [UCB]=166 nM (supersaturated). At low, physiological UCB concentrations, specific UCB uptake showed saturative kinetics with an apparent K(m) of 41 nM, indicating carrier-mediated transport. With aqueous supersaturation, UCB entered hepatocytes mainly by passive diffusion.
Mediavilla
M G
MG
Centro Studi Fegato, Department of Biochemistry, Biophysics and Chemistry of Macromolecules (BBCM), University of Trieste, Via Giorgeri 1, 34127, Trieste, Italy.
Pascolo
L
L
Rodriguez
J V
JV
Guibert
E E
EE
Ostrow
J D
JD
Tiribelli
C
C
D000818:Animals; D001663:Bilirubin / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012709:Serum Albumin / Q000493:pharmacokinetics; D013696:Temperature; D013997:Time Factors
D012709:Serum Albumin; D001663:Bilirubin