Localization and stoichiometry of electrogenic sodium bicarbonate cotransport in retinal glial cells

Eric A. Newman, Michael L. Astion

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

An electrogenic Na+/HCO 3− cotransport system was identified and characterized in freshly dissociated salamander Müller (glial) cells. Under voltage‐clamp, these cells generated an outward current when external HCO3 concentration ([HCO3]o) was raise. This current was Na+‐dependent, Cl‐independent, and was blocked by the stilbenes 4,4′‐diisothiocyanato‐stilbene‐2,2′‐disulfonate (DIDS) and 4,4′‐dinitrostilbene‐2,2′‐disulfonate (DNDS), and by harmaline, demonstrating that the current was generated by a Na+/HCO3 cotransport system. Substantially larger currents were evoked when [HCO3]o was raised at the Müller cell endfoot as compared to other cell regions, indicating that cotransporter sites are localized preferentially to the endfoot. The reversal potential of the current, which varied as a function of HCO3 and Na+ transmembrane gradients, indicated that the cotransporter has a HCO3:Na+ stoichiometry of 3:1.

Original languageEnglish (US)
Pages (from-to)424-428
Number of pages5
JournalGlia
Volume4
Issue number4
DOIs
StatePublished - 1991

Keywords

  • Müller cells
  • Salamander

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