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This Article Full Text Full Text (PDF) All Versions of this Article: 297/3/F693    most recent 00136.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Klokkers, J. Articles by Edemir, B. PubMed PubMed Citation Articles by Klokkers, J. Articles by Edemir, B.

Atrial natriuretic peptide and nitric oxide signaling antagonizes vasopressin-mediated water permeability in inner medullary collecting duct cells

¹Medizinische Klinik und Poliklinik D, Experimentelle Nephrologie, ²Centrum für Biomedizinische Optik und Photonik, and ³Institut für Physiologie II, Universitätsklinikum Münster, Münster; ⁴Bayer Schering Pharma, Wuppertal, Germany; and ⁵Department of Physiology, School of Medicine, University of Zagreb, Zagreb, Croatia

Submitted 9 March 2009 ; accepted in final form 23 June 2009

AVP and atrial natriuretic peptide (ANP) have opposite effects in the kidney. AVP induces antidiuresis by insertion of aquaporin-2 (AQP2) water channels into the plasma membrane of collecting duct principal cells. ANP acts as a diuretic factor. An ANP- and nitric oxide (NO)/soluble guanylate cyclase (sGC)-induced insertion of AQP2 into the plasma membrane is reported from different models. However, functional data on the insertion of AQP2 is missing. We used primary cultured inner medullary collecting duct (IMCD) cells and digital holographic microscopy, calcein-quenching measurements, and immunofluorescence and Western blotting to analyze the effects of ANP and NO donors on AQP2 phosphorylation, membrane expression, and water permeability. While AVP led to acceleration in osmotically induced swelling, ANP had no effect. However, in AVP-pretreated cells ANP significantly decreased the kinetics of cell swelling. This effect was mimicked by 8-bromo-cGMP and blunted by PKG inhibition. Stimulation of the NO/sGC pathway or direct activation of sGC with BAY 58-2667 had similar effects to ANP. In cells treated with AVP, AQP2 was predominantly localized in the plasma membrane, and after additional incubation with ANP AQP2 was mostly localized in the cytosol, indicating an increased retrieval of AQP2 from the plasma membrane by ANP. Western blot analysis showed that ANP was able to reduce AVP-induced phosphorylation of AQP2 at position S256. In conclusion, we show that the diuretic action of ANP or NO in the IMCD involves a decreased localization of AQP2 in the plasma membrane which is mediated by cGMP and PKG.

AQP2; cell volume kinetics; cGMP-generating signaling pathways; natriuretic peptides; water homeostasis; uroguanylin, phosphodiesterase-5