Involvement of guanylyl cyclase and cGMP in the regulation of Mrp2-mediated transport in the proximal tubule

• Published in: American journal of physiology. Renal physiology 2004-07, Vol.287 (1), p.F33-F38
• Main Authors: Notenboom, Sylvia, Miller, David S, Smits, P, Russel, Frans G M, Masereeuw, Rosalinde
• Format: Article
• Language: English
• Subjects: Animals; Cyclic GMP - pharmacology; Drug Resistance, Multiple; Endothelin-1 - pharmacology; Fundulidae - physiology; Gene Expression Regulation; Guanylate Cyclase - pharmacology; Kidney Tubules, Proximal - physiology; Membrane Transport Proteins - genetics; Membrane Transport Proteins - pharmacology; Mitochondrial Proteins; Multidrug Resistance-Associated Proteins - genetics; Multidrug Resistance-Associated Proteins - pharmacology; Nitric Oxide - metabolism; Protein Kinase C - pharmacology; Ribosomal Proteins; Signal Transduction
• ISSN: 1931-857X; 1522-1466
• DOI: 10.1152/ajprenal.00443.2003

In killifish renal proximal tubules, endothelin-1 (ET-1), acting through a basolateral ET(B) receptor, nitric oxide synthase (NOS), and PKC, decreases cell-to-lumen organic anion transport mediated by the multidrug resistance protein isoform 2 (Mrp2). In the present study, we examined the roles of guanylyl cyclase and cGMP in ET signaling to Mrp2. Using confocal microscopy and quantitative image analysis to measure Mrp2-mediated transport of the fluorescent drug fluorescein methotrexate (FL-MTX), we found that oxadiazole quinoxalin (ODQ), an inhibitor of NO-sensitive guanylyl cyclase, blocked ET-1 signaling. ODQ was also effective when signaling was initiated by nephrotoxicants (gentamicin, amikacin, diatrizoate, HgCl(2), and CdCl(2)), which appear to stimulate ET release from the tubules themselves. ODQ blocked the effects of the NO donor sodium nitroprusside but not of the phorbol ester that activates PKC. Exposing tubules to 8-bromo-cGMP (8-BrcGMP), a cell-permeable cGMP analog, decreased luminal FL-MTX accumulation. This effect was abolished by bisindoylmaleimide (BIM), a PKC inhibitor, but not by N(G)-methyl-l-arginine, a NOS inhibitor. Together, these data indicate that ET regulation of Mrp2 involves activation of guanylyl cyclase and generation of cGMP. Signaling by cGMP follows NO release and precedes PKC activation.