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Transport of fluorescent bile acids by the isolated perfused rat liver: Kinetics, sequestration, and mobilization
Author(s) -
Holzinger Fernando,
Schteingart Claudio D.,
TonNu HuongThu,
Cerrè Carolina,
Steinbach Joseph H.,
Yeh HongZen,
Hofmann Alan F.
Publication year - 1998
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.510280231
Subject(s) - mobilization , kinetics , chemistry , bile acid , fluorescence , biochemistry , biophysics , biology , physics , quantum mechanics , archaeology , history
Abstract Hepatocyte transport of six fluorescent bile acids containing nitrobenzoxadiazolyl (NBD) or a fluorescein derivative on the side chain was compared with that of natural bile acids using the single‐pass perfused rat liver. Compounds were infused at 40 nmol/g liver · min for 15 minutes; hepatic uptake and biliary recovery were measured; fractional extraction, intrinsic basolateral clearance, and sequestration (nonrecovery after 45 minutes of additional perfusion) were calculated. Fluorescent bile acids were efficiently extracted during the first 3 minutes (70%‐97%), but net extraction decreased with time mostly because of regurgitation into the perfusate. For cholylglycine and ursodeoxycholylglycine (UDC‐glycine), extraction was 94% to 99%, and regurgitation did not occur. Intrinsic hepatic clearance of fluorescent bile acids (2‐7 mL/g liver · min) was lower than that of cholylglycine (9.0 ± 0.6; mean ± SD) and UDC‐glycine (21.4 ± 0.4). Sequestration at 60 minutes was 8% to 26% for fluorescent bile acids with a cholyl moiety (cholylglycylaminofluorescein [CGamF], cholyllysylfluorescein [C‐L‐F], cholyl‐[Nϵ‐NBD]‐lysine [C‐L‐NBD], and cholylaminofluorescein [CamF]), 32% for ursodeoxycholylaminofluorescein (UDCamF), and 88% for ursodeoxycholyl‐(Nϵ‐NBD)‐lysine (UDC‐L‐NBD). Cholylglycine and UDC‐glycine had <3% retention. Biliary secretion of sequestered UDCamF, but not of UDC‐L‐NBD, was induced by adding dibutyryl cyclic adenosine monophosphate (DBcAMP) to the perfusate, possibly by translocation to the canaliculus of pericanalicular vesicles containing fluorescent bile acids. Biliary secretion of UDC‐L‐NBD, but not of UDCamF, was induced by adding cholyltaurine or UDC‐taurine, possibly by inhibition of binding to intracellular constituents or of transport into organelles. It is concluded that fluorescent bile acids are efficiently transported across the basolateral membrane, but in contrast to natural conjugated bile acids, are sequestered in the hepatocyte (UDC derivatives > cholyl derivatives). Two modes of hepatic sequestration of fluorescent bile acids were identified. Fluorescent bile acids may be useful to characterize sequestration processes during bile acid transport through the hepatocyte.