title: Altered hepatobiliary disposition of 5 (and 6)-carboxy-2',7'-dichlorofluorescein in Abcg2 (Bcrp1) and Abcc2 (Mrp2) knockout mice.
abstract: This study characterized the hepatobiliary disposition of 5 (and 6)-carboxy-2',7'-dichlorofluorescein (CDF), a model Abcc2/Mrp2 (canalicular) and Abcc3/Mrp3 (basolateral) substrate, in perfused livers from male C57BL/6 wild-type, Abcg2-/-, and Abcc2-/- mice. After single-pass liver perfusion with 1 muM CDF diacetate for 30 min and an additional 30-min perfusion with CDF-free buffer, cumulative biliary excretion of CDF in Abcg2-/- mice was significantly higher than in wild-type mice (65 +/- 6 and 47 +/- 15% of dose, respectively, p < 0.05), whereas CDF recovery in bile of Abcc2-/- mice was negligible. Cumulative recovery of CDF in perfusate was significantly higher in Abcc2-/- (90 +/- 8% of dose) relative to wild-type (35 +/- 11% of dose) mice. Compartmental pharmacokinetic analysis revealed that the rate constant for CDF biliary excretion was significantly increased in Abcg2-/- (0.061 +/- 0.005 min(-1)) compared with wild-type (0.039 +/- 0.011 min(-1)) mice. The rate constant governing the basolateral excretion of CDF was approximately 4-fold higher in Abcc2-/- (0.12 +/- 0.02 min(-1)) relative to wild-type (0.030 +/- 0.011 min(-1)) mice but was not altered in Abcg2-/- (0.031 +/- 0.004 min(-1)) mice. Hepatic Abcc3 protein levels, determined by immunoblot analysis, were approximately 60% higher in Abcc2-/- mice than in wild-type mice. In contrast, neither Abcc3 protein levels nor Abcc2 mRNA levels were altered in Abcg2-/- relative to wild-type mice. These data in knockout mouse models demonstrate that loss of expression and function of one canalicular transport protein may change the route and/or extent of excretion into bile or perfusate because of alterations in the function of other basolateral or canalicular transport proteins.
authors.affiliation: School of Pharmacy, CB# 7360, Kerr Hall, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7360, USA.
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Nezasa
authors.forename: Xianbin
authors.initials: X
authors.lastname: Tian
authors.forename: Maciej J
authors.initials: MJ
authors.lastname: Zamek-Gliszczynski
authors.forename: Nita J
authors.initials: NJ
authors.lastname: Patel
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Raub
authors.forename: Kim L R
authors.initials: KL
authors.lastname: Brouwer
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000818:Animals; D001646:Bile / Q000378:metabolism*; D005452:Fluoresceins / Q000493:pharmacokinetics*; D005786:Gene Expression Regulation; D008099:Liver / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger; D015854:Up-Regulation
chemical_list: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D005452:Fluoresceins; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger; C501412:Abcg2 protein, mouse; C053897:5(6)-carboxy-2',7'-dichlorofluorescein; C114462:multidrug resistance-associated protein 3