Activation of dopamine D1-like receptors induces acute internalization of the renal Na+/phosphate cotransporter NaPi-IIa in mouse kidney and OK cells

Desa Bacic, Paola Capuano, Michel Baum, Jianning Zhang, Gerti Stange, Jürg Biber, Brigitte Kaissling, Orson W. Moe, Carsten A. Wagner, Heini Murer

Research output: Contribution to journalArticle

59 Scopus citations

Abstract

The Na+/phosphate cotransporter NaPi-IIa (SLC34A1) is the major transporter mediating the reabsorption of Pi in the proximal tubule. Expression and activity of NaPi-IIa is regulated by several factors, including parathyroid hormone, dopamine, metabolic acidosis, and dietary Pi intake. Dopamine induces natriuresis and phosphaturia in vivo, and its actions on several Na+-transporting systems such as NHE3 and Na +-K+-ATPaSe have been investigated in detail. Using freshly isolated mouse kidney slices, perfused proximal tubules, and cultured renal epithelial cells, we examined the acute effects of dopamine on NaPi-IIa expression and localization. Incubation of isolated kidney slices with the selective Di-like receptor agonists fenoldopam (10 μM) and SKF-38393 (10 μM) for 1 h induced NaPi-IIa internalization and reduced expression of NaPi-IIa in the brush border membrane (BBM). The D2-like selective agonist quinpirole (1 μM) had no effect. The D1 and D2 agonists did not affect the renal Na+/sulfate cotransporter NaSi in the BBM of the proximal tubule. Studies with isolated perfused proximal tubules demonstrated that activation of luminal, but not basolateral, D1-like receptors caused NaPi-IIa internalization. In kidney slices, inhibition of PKC (1 μM chelerythrine) or ERK1/2 (20 μM PD-098089) pathways did not prevent the fenoldopam-induced internalization. Inhibition with the PKA blocker H-89 (10 μM) abolished the effect of fenoldopam. Immunoblot demonstrated a reduction of NaPi-IIa protein in BBMs from kidney slices treated with fenoldopam. Incubation of opossum kidney cells transfected with NaPi-IIa-green fluorescent protein chimera shifted fluorescence from the apical membrane to an intracellular pool. In summary, dopamine induces internalization of NaPi-IIa by activation of luminal D1-like receptors, an effect that is mediated by PKA.

Original languageEnglish (US)
Pages (from-to)F740-F747
JournalAmerican Journal of Physiology - Renal Physiology
Volume288
Issue number4 57-4
DOIs
StatePublished - Apr 1 2005

Keywords

  • Brush border membrane
  • Protein kinase A
  • Proximal tubule

ASJC Scopus subject areas

  • Physiology
  • Urology

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