Fig. 1.

Model of the functional role of NTCP in hepatic bile acid transport and metabolism. Transport of bile acids from portal blood into hepatocytes via NTCP depends on a sodium gradient and is inhibited by CsA or ezetimibe. Secretion into the bile canaliculus via bile salt export pump (BSEP) in an ATP-dependent manner and synthesis from cholesterol are regulated by bile acid-mediated activation of FXR. cAMP mediates dephosphorylation and membrane translocation of NTCP. NTCP sodium taurocholate co-transporting polypeptide, BSEP bile salt export pump, FXR Farnesoid X Receptor, SHP small heterodimer partner, CYP7A1 cholesterol 7α-hydroxylase, BA bile acid, TJ tight junction, CsA cyclosporin A, cAMP cyclic adenosine monophosphate