Anion conductance behavior of the glutamate uptake carrier in salamander retinal glial cells

Brian Billups, David Rossi, David Attwell

Research output: Contribution to journalArticle

96 Scopus citations

Abstract

Glutamate uptake is driven by the cotransport of Na+ ions, the countertransport of K+ ions, and either the countertransport of OH or the cotransport of H+ ions. In addition, activating glutamate uptake carriers has been shown to lead to activation of an anion conductance present in the carrier structure. Here we characterize the ion selectivity and gating of this anion conductance. The conductance is small with Cl- as the permeant anion, but it is large with NO3 or ClO4 present, undermining the earlier use of NO3 and ClO4 to suggest that OH countertransport rather than H+ cotransport helps drive uptake. Activation of the anion conductance can be evoked by extra- or intracellular glutamate and can occur even when glutamate transport is inhibited. By running the carrier backward and detecting glutamate release with AMPA receptors in neurons placed near the glial cells, we show that anion flux is not coupled thermodynamically to glutamate movement, but OH-/H+ transport is. The possibility that cell excitability is modulated by the anion conductance associated with glutamate uptake suggests a target for therapeutic drugs to reduce glutamate release in conditions like epilepsy.

Original languageEnglish (US)
Pages (from-to)6722-6731
Number of pages10
JournalJournal of Neuroscience
Volume16
Issue number21
DOIs
StatePublished - Nov 1 1996

Keywords

  • anion conductance
  • glial cell
  • glutamate
  • pH
  • transporter
  • uptake

ASJC Scopus subject areas

  • Neuroscience(all)

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