Premium
Effect of Glutamine on Glutamate Release from Hippocampal Slices Induced by High K + or by Electrical Stimulation: Interaction with Different Ca 2+ Concentrations
Author(s) -
Szerb John C.,
O'Regan Patrick A.
Publication year - 1985
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1985.tb07160.x
Subject(s) - glutamine , glutamate receptor , tetrodotoxin , stimulation , extracellular , amino acid , biophysics , liberation , biochemistry , glutamic acid , chemistry , biology , medicine , endocrinology , in vitro , receptor
To characterize the effect of glutamine on the release of glutamate, aspartate, and γ‐aminobutyric acid (GABA), rat hippocampal slices were superfused with different concentrations of glutamine or Ca 2+ . Amino acids released and retained were analyzed by HPLC. Glutamine (0.5 mmol/L) increased more than threefold the release of glutamate evoked by 50 mmol/L K + in the presence of 2.6 mmol/L Ca 2+ without a corresponding increase in glutamate content, while the release of aspartate was increased less and that of GABA not at all by glutamine. The evoked release of all three amino acids, including the enhanced release of glutamate in the presence of glutamine, was strongly dependent on Ca 2+ concentrations between 0.1 and 2.6 mmol/L. The potentiation of glutamate release by glutamine reached a plateau at 0.25 mmol/L glutamine. Intermittent electrical field stimulation increased the release of only glutamate and this release was nearly doubled by glutamine. The increased release was Ca 2+ dependent and tetrodotoxin (TTX) sensitive. Results suggest that extracellular glutamine promotes primarily the formation of releasable glutamate and this enhancement is dependent on extracellular Ca 2+ .