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Journal of Hepato-Biliary-Pancreatic Surgery

, Volume 9, Issue 4, pp 443–447 | Cite as

Hepatobiliary transport of bile acids and organic anions

  • Hajime Takikawa
Basic knowledge of interest

Abstract.

Recent studies have elucidated the mechanism and regulation of hepatic transport of bile acids and organic anions. Bile acids are taken up into hepatocytes by basolateral transporters, Na+-dependently by Na+/taurocholate cotransporting polypeptide (NTCP) and Na+-independently by organic anion transporting polypeptide (OATP) families. Organic anions are taken up into hepatocytes by OATP families. These compounds are then transported in hepatocytes bound to cytosolic binders, and subjected to transport by ATP binding cassette (ABC) transporters at the canalicular membrane. Amidated bile acids are excreted into bile by bile salt export pump (BSEP), and organic anions and bile acid sulfates and glucuronides are excreted by multidrug resistance protein 2 (MRP2). Hepatic transporters are downregulated under cholestasis in rats and humans, except for MRP3, a basolateral ABC transporter, which is upregulated and may have a role in removing bile acids and organic anions from hepatocytes to the blood under cholestatic conditions. Nuclear receptors, which bind bile acids, have been shown to regulate the expression of hepatic transporters. Farnesoid X receptor (FXR), which downregulates CYP7A1, the rate-limiting enzyme of bile acid biosynthesis, upregulates BSEP and downregulates NTCP. MRP2 is upregulated by both FXR and pregnane X receptor (PXR), which upregulates CYP3A.

Key words Bile acid   Organic anions   Bile salt export pump (Bsep)   Multidrug resistance protein 2 (Mrp2) 

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Copyright information

© Springer-Verlag Tokyo 2002

Authors and Affiliations

  • Hajime Takikawa
    • 1
  1. 1.Department of Medicine, Teikyo University School of Medicine, Itabashi, Tokyo 173-8605, JapanJP

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