Effect of acetaminophen on expression and activity of rat liver multidrug resistance-associated protein 2 and P-glycoprotein.
We evaluated the effect of acetaminophen (APAP), given as a single, 1g/kg body weight dose, on expression and activity of rat liver multidrug resistance-associated protein 2 (Mrp2) and P-glycoprotein (P-gp), two major canalicular drug transporters. The studies were performed 24h after administration of the drug. APAP induced an increase in plasma membrane content of Mrp2 detected by western blotting, consistent with increased detection of the protein at the canalicular level by immunoflourescence microscopy. In vivo biliary excretion of dinitrophenyl-S-glutathione, a well known Mrp2 substrate, was slightly but significantly increased by APAP, agreeing well with upregulation of the transporter. Basal biliary excretion of oxidized glutathione, an endogenous Mrp2 substrate, was also increased by APAP, likely indicating increased hepatic synthesis as a result of APAP-induced oxidative stress followed by accelerated canalicular secretion mediated by Mrp2. APAP also increased the expression of P-gp detected by western blotting and immunofluorescence microscopy as well as the in vivo biliary secretory rate of digoxin, a model P-gp substrate. Because specific APAP-conjugated metabolites are Mrp2 substrates, we postulate that induction of Mrp2 by APAP may represent an adaptive mechanism to accelerate liver disposition of the drug. In addition, increased Mrp2-mediated elimination of oxidized glutathione may be essential in maintaining the redox equilibrium in the hepatocyte under conditions of APAP-induced oxidative stress.
Cátedra de Fisiopatología, Departamento de Ciencias Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
Carolina I
CI
Ghanem
Paula C
PC
Gómez
María C
MC
Arana
María
M
Perassolo
María L
ML
Ruiz
Silvina S M
SS
Villanueva
Elena J
EJ
Ochoa
Viviana A
VA
Catania
Laura A
LA
Bengochea
Aldo D
AD
Mottino
D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics / Q000378:metabolism*; D000082:Acetaminophen / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D018435:ATP Binding Cassette Transporter, Subfamily B; D000082:Acetaminophen; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins