Glutamate impairs neuronal calcium extrusion while reducing sodium gradient

Neuron. 1994 Feb;12(2):295-300. doi: 10.1016/0896-6273(94)90272-0.


The rate of decrease of neuronal [Ca2+]i after an elevation induced by a glutamate pulse is much slower than that after a comparable [Ca2+]i elevation induced by a K+ depolarization. To investigate whether the [Na+]i increase taking place during the glutamate pulse reduces the rate of Ca2+ extrusion, we monitored simultaneously [Na+]i and [Ca2+]i during a K+ depolarization and a glutamate pulse lasting 1 min. The K+ depolarization evoked only a transient increase of [Na+]i from 4 mM to 13 mM, whereas the glutamate pulse increased [Na+]i to 60 mM, and this increase persisted after glutamate removal. An application of bepridil immediately after glutamate pulse when [Na+]i was greatly elevated, but not 14 min after glutamate removal when a basal [Na+]i was restored, evoked a [Ca2+]i increase accompanied by a decrease of [Na+]i, indicating a reverse mode of operation of the Na+/Ca2+ exchanger. These data suggest that the glutamate-evoked increase in [Na+]i may play a role in Ca2+ homeostasis destabilization.

Publication types

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

MeSH terms

  • Animals
  • Bepridil / pharmacology
  • Calcium / metabolism*
  • Cerebellum / cytology
  • Electrophysiology
  • Glutamates / pharmacology*
  • Glutamic Acid
  • Granulocytes / drug effects
  • Granulocytes / metabolism
  • Neurons / drug effects
  • Neurons / metabolism*
  • Neurons / physiology
  • Osmolar Concentration
  • Potassium / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Sodium / metabolism*


  • Glutamates
  • Glutamic Acid
  • Bepridil
  • Sodium
  • Potassium
  • Calcium