Ion fluxes associated with excitatory amino acid transport

Neuron. 1995 Sep;15(3):721-8. doi: 10.1016/0896-6273(95)90159-0.


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- > 1- > 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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Aspartic Acid / metabolism
  • Biological Transport
  • Brain / metabolism
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Chlorides / metabolism
  • Electric Conductivity
  • Excitatory Amino Acids / metabolism*
  • Female
  • Glutamic Acid / metabolism
  • Humans
  • Ion Channel Gating
  • Ion Channels / physiology*
  • Oocytes / metabolism
  • Patch-Clamp Techniques
  • Thermodynamics
  • Transfection
  • Xenopus


  • Carrier Proteins
  • Chlorides
  • Excitatory Amino Acids
  • Ion Channels
  • Aspartic Acid
  • Glutamic Acid