Abstract
The handling of many organic anions by the liver involves at least three steps, namely hepatic uptake, intracellular transport and biliary excretion. In addition, conjugation and/or other metabolic alterations may occur prior to excretion. Overall hepatic transport from the blood into the bile of a variety of organic anions has been studied in some detail. It has been demonstrated that the overall transport of anionic dyes such as sulfobromophthalein (BSP) (12,25), indocyanine green (ICG)(15) and bilirubin (20,23) as well as of bile acids (10, l4, l6, 22, 24) is a saturable process that may be characterized by an excretory transport maximum. Information on the mechanisms responsible for hepatic uptake of organic anions and their relation to overall hepatic transport, however, is still incomplete. Studies of hepatic ESP uptake by Goresky (7) and of taurocholate uptake by Glasinovic et al (6) and by our group (19) have shown that the kinetics of hepatic uptake of anionic dyes as well as of bile acids are consistent with carrier-mediated transport. The nature and location of this hypothetical carrier remain to be elucidated. Furthermore, it is unclear whether a single or multiple transport systems are present for the hepatic uptake of organic anions.
Published Version
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