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Uptake of [ 3 H]bilirubin in freshly isolated rat hepatocytes: role of free bilirubin concentration
Author(s) -
Mediavilla Maria Gabriela,
Pascolo Lorella,
Rodriguez Joaquin V.,
Guibert Edgardo E.,
Ostrow J.Donald,
Tiribelli Claudio
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)01606-3
Subject(s) - supersaturation , bilirubin , chemistry , kinetics , aqueous solution , albumin , solubility , hepatocyte , diffusion , chromatography , biophysics , biochemistry , in vitro , endocrinology , biology , physics , organic chemistry , quantum mechanics , thermodynamics
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.