Involvement of an Organic Anion Transporter (Canalicular Multispecific Organic Anion Transporter/Multidrug Resistance-Associated Protein 2) in Gastrointestinal Secretion of Glutathione Conjugates in Rats

  1. Yasumasa Gotoh1,
  2. Hiroshi Suzuki1,2,
  3. Setsuo Kinoshita1,
  4. Tomoko Hirohashi1,2,
  5. Yukio Kato1,2 and
  6. Yuichi Sugiyama1,2
  1. 1Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo (Y.G., H.S., S.K., T.H., Y.K., Y.S.); and 2Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, Kawaguchi City, Japan (H.S., T.H., Y.K.,Y.S.)

    Abstract

    We investigated the role of cMOAT/MRP2 (canalicular multispecific organic anion transporter/multidrug resistance-associated protein 2) in the intestinal secretion of organic anions by comparing the behavior in Sprague-Dawley (SD) rats and Eisai hyperbilirubinemic rat (EHBR) whose cMOAT/MRP2 is hereditarily defective. After i.v. administration of 1-chloro-2,4-dinitrobenzene (30 μmol/kg), the biliary and intestinal excretion of its glutathione conjugate 2,4-dinitrophenyl-S-glutathione (DNP-SG), a substrate for cMOAT/MRP2, was significantly reduced in EHBR compared with SD rats. This result also was confirmed by Ussing chamber studies; DNP-SG showed 1.5-fold greater serosal-to-mucosal flux compared with the mucosal-to-serosal flux in SD rats, whereas a similar flux was observed in both directions in EHBR. In addition, metabolic inhibitors reduced the preferential serosal-to-mucosal flux of DNP-SG in SD rats. In everted sac studies, intestinal secretion clearance, defined as the efflux rate of DNP-SG into the mucosal side divided by the area under the curve on the serosal side, was significantly lower in the jejunum of EHBR than that in SD rats. Northern blot analyses demonstrated the highest mRNA level of cMOAT/MRP2 in the jejunum, which is in good agreement with the results of the everted sac studies. These results suggest that cMOAT/MRP2 is involved in the secretion of organic anions in the small intestine.

    Footnotes

    • Send reprint requests to: Dr. Yuichi Sugiyama, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. E-mail:sugiyama{at}seizai.f.u-tokyo.ac.jp

    • Abbreviations:
      mdr
      multidrug resistant
      P-gp
      P-glycoprotein
      cMOAT
      canalicular multispecific organic anion transporter
      MRP
      multidrug resistance-associated protein
      TR−
      transport deficient rats
      EHBR
      Eisai hyperbilirubinemic rats
      CDNB
      1-chloro-2,4-dinitrobenzene
      FDNB
      1-fluoro-2,4-dinitrobenzene
      SD rats
      Sprague-Dawley rats
      DNP-SG
      2,4-dinitrophenyl-S-glutathione
      DNP-CG
      2,4-dinitrophenyl-S-cysteinylglycine
      DNP-Nac
      2,4-dinitrophenyl-N-acetylcysteine
      DNP-Cys
      2,4-dinitrophenyl-S-cysteine
      AUC
      area under the curve
      G3PDH
      glyceraldehyde 3-phosphate dehydrogenase
      LTC4
      leukotriene C4
      NAcLTE4
      N-acetyl leukotriene E4
      • Received June 14, 1999.
      • Accepted October 4, 1999.
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    1. JPET January 1, 2000 vol. 292 no. 1 433-439
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