title: Site-specific bidirectional efflux of 2,4-dinitrophenyl-S-glutathione, a substrate of multidrug resistance-associated proteins, in rat intestine and Caco-2 cells.
abstract: The site-specific function of multidrug-resistance-associated proteins (MRPs), especially MRP2 and MRP3, was examined in rat intestine and human colon adenocarcinoma (Caco-2) cells. The MRP function was evaluated pharmacokinetically by measuring the efflux transport of 2,4-dinitrophenyl-S-glutathione (DNP-SG), an MRP substrate, after application of 1-chloro-2,4-dinitrobenzene (CDNB), a precursor of DNP-SG. The expression of rat and human MRP2 and MRP3 was analysed by Western blotting. The rat jejunum exhibited a higher apical MRP2 and a lower basolateral MRP3 expression than ileum. In accordance with the expression level, DNP-SG efflux to the mucosal surface was significantly greater in jejunum, while serosal efflux was greater in ileum. Site-specific bidirectional efflux of DNP-SG was also observed in in-vivo studies, in which portal and femoral plasma levels and biliary excretion rate of DNP-SG were significantly higher when CDNB was administered to ileum. Caco-2 cells also showed a bidirectional efflux of DNP-SG. Probenecid, an MRP inhibitor, significantly suppressed the mucosal efflux in jejunum and serosal efflux in ileum. In contrast, probenecid significantly suppressed both apical and basolateral efflux of DNP-SG in Caco2 cells, though the inhibition was of small magnitude. In conclusion, the efflux of DNP-SG from enterocytes mediated by MRPs exhibited a significant regional difference in rat intestine, indicating possible variability in intestinal bioavailabilities of MRP substrates, depending on their absorption sites along the intestine.
authors: Department of Pharmaceutics and Therapeutics, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan.
authors: Tomoharu
authors: T
authors: Yokooji
authors: Teruo
authors: T
authors: Murakami
authors: Ryoko
authors: R
authors: Yumoto
authors: Junya
authors: J
authors: Nagai
authors: Mikihisa
authors: M
authors: Takano
mesh_terms: D000818:Animals; D001646:Bile / Q000378:metabolism; D001682:Biological Availability; D001692:Biological Transport; D015153:Blotting, Western; D018938:Caco-2 Cells; D004137:Dinitrochlorobenzene; D005978:Glutathione / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D006801:Humans; D007082:Ileum / Q000378:metabolism; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism; D007583:Jejunum / Q000378:metabolism; D008297:Male; D026901:Membrane Transport Proteins / Q000378:metabolism*; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism*; D011339:Probenecid; D051381:Rats; D017207:Rats, Sprague-Dawley; D013379:Substrate Specificity
chemical_list: D004137:Dinitrochlorobenzene; D005978:Glutathione; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011339:Probenecid; C000715087:ABCC2 protein, human; C114462:multidrug resistance-associated protein 3; C030190:S-(2,4-dinitrophenyl)glutathione