Electrogenic glutamate uptake in glial cells is activated by intracellular potassium
- 1 September 1988
- journal article
- letter
- Published by Springer Science and Business Media LLC in Nature
- Vol. 335 (6189), 433-435
- https://doi.org/10.1038/335433a0
Abstract
Uptake of glutamate into glial cells in the CNS maintains the extracellular glutamate concentration below neurotoxic levels and helps terminate its action as a neurotransmitter 1. The co-transport of two sodium ions on the glutamate carrier is thought to provide the energy needed to transport glutamate into cells2,3. We have shown recently that glutamate uptake can be detected electrically because the excess of Na+ ions transported with each glutamate anion results in a net current flow into the cell4. We took advantage of the control of the environment, both inside and outside the cell, provided by whole-cell patch-clamping and now report that glutamate uptake is activated by intracellular potassium and inhibited by extracellular potassium. Our results indicate that one K+ ion is transported out of the cell each time a glutamate anion and three Na+ ions are transported in. A carrier with this stoichiometry can accumulate glutamate against a much greater concentration gradient than a carrier co-transporting one glutamate anion and two Na+ ions. Pathological rises in extracellular potassium concentration will inhibit glutamate uptake by depolarizing glial cells and by preventing the loss of K+ from the glutamate carrier. This will facilitate a rise in the extracellular glutamate concentration to neurotoxic levels and contribute to the neuronal death occurring in brain anoxia and ischaemia.Keywords
This publication has 10 references indexed in Scilit:
- The physiology of excitatory amino acids in the vertebrate central nervous systemProgress in Neurobiology, 1987
- Excitotoxity and the NMDA receptorTrends in Neurosciences, 1987
- Electrogenic glutamate uptake is a major current carrier in the membrane of axolotl retinal glial cellsNature, 1987
- The role of glial cells in regulation of neurotransmitter amino acids in the external environment. II. Mechanism of aspartate transportBrain Research, 1986
- Voltage-dependent calcium and potassium channels in retinal glial cellsNature, 1985
- Functional interactions between neurons and astrocytes. II. Potassium homeostasis at the cellular levelProgress in Neurobiology, 1983
- Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patchesPflügers Archiv - European Journal of Physiology, 1981
- COUPLED TRANSPORT OF GLUTAMATE AND SODIUM IN A CEREBELLAR NERVE CELL LINEJournal of Neurochemistry, 1979
- Functional interactions between neurons and astrocytes I. Turnover and metabolism of putative amino acid transmittersProgress in Neurobiology, 1979
- Active transport of L-glutamate by membrane vesicles isolated from rat brainBiochemistry, 1978