OKP cells express the Na-dicarboxylate cotransporter NaDC-1

Seiji Aruga, Ana M. Pajor, Kiyoshi Nakamura, Liping Liu, Orson W. Moe, Patricia A. Preisig, Robert J. Alpern

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15 Scopus citations


Urinary citrate concentration, a major factor in the formation of kidney stones, is primarily determined by its rate of reabsorption in the proximal tubule. Citrate reabsorption is mediated by the Na-dicarboxylate cotransporter-1 (NaDC-1). The opossum kidney (OKP) cell line possesses many characteristics of the renal proximal tubule. The OKP NaDC-1 (oNaDC-1) cDNA was cloned and encodes a 2.4-kb mRNA. When injected into Xenopus oocytes, the cotransporter is expressed and demonstrates Na-coupled citrate transport with a stoichiometry of ≥3 Na:1 citrate, specificity for di- and tricarboxylates, pH-dependent citrate transport, and pH-independent succinate transport, all characteristics of the other NaDC-1 orthologs. Chronic metabolic acidosis increases proximal tubule citrate reabsorption, leading to profound hypocitraturia and an increased risk for stone formation. Under the conditions studied, endogenous OKP NaDC-1 mRNA abundance is not regulated by changes in media pH. In OKP cells transfected with a green fluorescent protein-oNaDC-1 construct, however, media acidification increases Na-dependent citrate uptake, demonstrating posttranscriptional acid regulation of NaDC-1 activity.

Original languageEnglish (US)
Pages (from-to)C64-C72
JournalAmerican Journal of Physiology - Cell Physiology
Issue number1 56-1
StatePublished - Jul 2004


  • Acid base
  • Citrate
  • Nephrocalcinosis
  • Nephrolithiasis
  • Opossum kidney cells

ASJC Scopus subject areas

  • Physiology
  • Cell Biology


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