title: Confocal imaging with a fluorescent bile acid analogue closely mimicking hepatic taurocholate disposition.
abstract: This study aimed to characterize the in vitro hepatic transport mechanisms in primary rat and human hepatocytes of the fluorescent bile acid derivative N-(24-[7-(4-N,N-dimethylaminosulfonyl-2,1,3-benzoxadiazole)]amino-3α,7α,12α-trihydroxy-27-nor-5β-cholestan-26-oyl)-2'-aminoethanesulfonate (tauro-nor-THCA-24-DBD), previously synthesized to study the activity of the bile salt export pump (BSEP). The fluorescent bile acid derivative exhibited saturable uptake kinetics in suspended rat hepatocytes. Hepatic uptake was inhibited in the presence of substrates/inhibitors of the organic anion transporting polypeptide (Oatp) family and Na(+) -taurocholate cotransporting peptide (Ntcp). Concentration-dependent uptake of the fluorescent bile acid was also saturable in Chinese hamster ovary cells transfected with rNtcp, hNTCP, OATP1B1, or OATP1B3. The fluorescent bile acid derivative was actively excreted in the bile canaliculi of sandwich-cultured rat and human hepatocytes (SCRH and SCHH), with a biliary excretion index (BEI) of 26% and 32%, respectively. In SCRH, cyclosporin A significantly decreased the BEI to 5%. Quantification by real-time confocal imaging further confirmed canalicular transport of the fluorescent bile acid derivative (BEI = 75%). We conclude that tauro-nor-THCA-24-DBD is a useful probe to study interference of drugs with NTCP/Ntcp- and BSEP/Bsep-mediated transport in fluorescence-based in vitro assays.
authors.affiliation: Drug Delivery and Disposition, KU Leuven Department of Pharmaceutical and Pharmacological Sciences, O&N2, Leuven, 3000, Belgium.
authors.forename: Tom
authors.initials: T
authors.lastname: De Bruyn
authors.forename: Wouter
authors.initials: W
authors.lastname: Sempels
authors.forename: Jan
authors.initials: J
authors.lastname: Snoeys
authors.forename: Nico
authors.initials: N
authors.lastname: Holmstock
authors.forename: Sagnik
authors.initials: S
authors.lastname: Chatterjee
authors.forename: Bruno
authors.initials: B
authors.lastname: Stieger
authors.forename: Patrick
authors.initials: P
authors.lastname: Augustijns
authors.forename: Johan
authors.initials: J
authors.lastname: Hofkens
authors.forename: Hideaki
authors.initials: H
authors.lastname: Mizuno
authors.forename: Pieter
authors.initials: P
authors.lastname: Annaert
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000737:chemistry*; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D005456:Fluorescent Dyes / Q000737:chemistry*; D008099:Liver / Q000378:metabolism*; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar; D013656:Taurocholic Acid / Q000378:metabolism* / Q000493:pharmacokinetics
chemical_list: D001647:Bile Acids and Salts; D005456:Fluorescent Dyes; D013656:Taurocholic Acid
keywords: drug interactions; drug transport; hepatic transport; hepatobiliary disposition; hepatocytes; organic anion-transporting polypeptide transporters