Involvement of Mrp2 in Hepatic and Intestinal Disposition of Dinitrophenyl-S-glutathione in Partially Hepatectomized Rats

VILLANUEVA SSM; RUIZ ML; LUQUITA MG; SÁNCHEZ POZZI EJ; CATANIA VA; MOTTINO AD

Toxicological Sciences

Oxford Journal

Año: 2005 vol. 84 p. 4 - 11

The ability of the liver and small intestine for secretion ofdinitrophenyl-S-glutathione (DNP-SG), a substrate for multidrugresistance-associated protein 2 (Mrp2), into bile and lumen, respectively,as well as expression of Mrp2 in both tissues, were assessed in70?75% hepatectomized rats. An in vivo perfused intestinal modelwas used. A single iv dose of 30 mmol/kg b.w. of 1-chloro-2,4-dinitrobenzene (CDNB) was administered and its glutathione conjugate,DNP-SG, was determined by HPLC in bile and intestinalperfusate. One and seven days after hepatectomy, biliary excretionof DNP-SG was decreased by 90 and 50% with respect to shams,respectively, when expressed per mass unit. In contrast, intestinalexcretion was increased by 63% or unchanged one and seven dayspost-hepatectomy, respectively. Tissue content of DNP-SG 5 minafter CDNB administration was substantially decreased in liverand significantly increased in intestine, one day post-hepatectomy.Western and immunofluorescence studies revealed preserved levelsand localization of Mrp2 in both tissues from hepatectomizedanimals, irrespective of the time analyzed. In spite of preservedexpression of Mrp2, the higher availability of DNP-SG in intestinalcells, likely as a consequence of increased glutathione-S-transferasemediatedconjugation of CDNB, may explain the in vivo findings.Further experiments in isolated hepatocytes suggested thatdecreased synthesis of DNP-SG rather than altered canaliculartransport is responsible for the substantial impairment in excretionof this compound into bile. Taken together, these results indicatethat the intestine may partially compensate for liver DNP-SGdisposition, particularly shortly after surgery, while liver capabilityis recovering.