title: Short-term regulation of multidrug resistance-associated protein 3 in rat and human hepatocytes.
abstract: The short-term regulation of multidrug resistance-associated protein 3 (Mrp3/MRP3) by cAMP and PKC was investigated in sandwich-cultured rat and human hepatocytes and isolated perfused rat livers. The modulator glucagon (500 nM) and the phorbol ester PMA (0.1 muM) were utilized to increase intracellular cAMP and PKC levels, respectively. In glucagon-treated rat hepatocytes, efflux of the Mrp3 substrate 5-(6)-carboxy-2',7'-dichlorofluorescein (CDF) increased approximately 1.5-fold, even in hepatocytes treated with the organic anion transporter (Oatp) inhibitor sulfobromophthalein (BSP). Confocal microscopy revealed more concentrated Mrp3 fluorescence in the basolateral membrane (less diffuse staining pattern) with glucagon treatment. PMA had no effect on Mrp3 activity or localization in sandwich-cultured rat hepatocytes. Glucagon and PMA treatment in isolated perfused rat livers resulted in a threefold increase (14 +/- 4.6 mul.min(-1).g liver(-1)) and a fourfold decrease (1.3 +/- 0.3 mul.min(-1).g liver(-1)) in CDF basolateral clearance compared with control livers (4.7 +/- 2.3 mul.min(-1).g liver(-1)), whereas CDF biliary clearance was not statistically different. In sandwich-cultured human hepatocytes, glucagon treatment resulted in a 1.3-fold increase in CDF efflux and a concomitant increase in MRP3 fluorescence in the basolateral membrane. In summary, cAMP and PKC appear to be involved in the short-term regulation of Mrp3/MRP3, as demonstrated by alterations in activity and localization in rat and human hepatocytes.
authors.affiliation: 3205 Kerr Hall, School of Pharmacy, Univ. of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7360, USA.
authors.forename: Priyamvada
authors.initials: P
authors.lastname: Chandra
authors.forename: Peijin
authors.initials: P
authors.lastname: Zhang
authors.forename: Kim L R
authors.initials: KL
authors.lastname: Brouwer
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000502:physiology*; D018528:ATP-Binding Cassette Transporters / Q000502:physiology*; D000818:Animals; D018929:Cell Culture Techniques; D000242:Cyclic AMP / Q000494:pharmacology*; D018432:Drug Resistance, Multiple; D005934:Glucagon / Q000378:metabolism; D022781:Hepatocytes / Q000502:physiology*; D006801:Humans; D008099:Liver / Q000502:physiology; D011493:Protein Kinase C / Q000494:pharmacology*; D051381:Rats
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D018528:ATP-Binding Cassette Transporters; D005934:Glucagon; C095122:multidrug resistance protein 3; D000242:Cyclic AMP; D011493:Protein Kinase C