Ion fluxes associated with excitatory amino acid transport

Jacques I. Wadiche, Susan G. Amara, Michael P. Kavanaugh

Research output: Contribution to journalArticlepeer-review

Abstract

Flux of substrate and charge mediated by three cloned excitatory amino acid transporters widely expressed in human brain were studied in voltage-clamped Xenopus oocytes. Superfusion of l-glutamate or d-aspartate resulted in currents due in part to electrogenic Na+ cotransport, which contributed 1 net positive charge per transport cycle. A significant additional component of the currents was due to activation of a reversible anion flux that was not thermodynamically coupled to amino acid transport. The selectivity sequence of this ligand-activated conductance was NO3- > I- > Br- > Cl- > F-. The results suggest that these proteins mediate both transporter- and channel-like modes of permeation, providing a potential mechanism for dampening cell excitability, in addition to removal of transmitter.

Original languageEnglish
Pages (from-to)721-728
Number of pages8
JournalNeuron
Volume15
Issue number3
DOIs
StatePublished - Sep 1995

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