Measurement of glutamate uptake and reversed transport by rat synaptosome transporters

Atsushi Nishida, Hiroshi Iwata, Yukitsuka Kudo, Tsutomu Kobayashi, Yuzo Matsuoka, Yoshikatsu Kanai, Hitoshi Endou

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    5 Citations (Scopus)


    To establish an assay system for evaluation of the uptake and reversed transport of glutamate, we examined the effects of Na+-concentration and pharmacological agents on the extracellular glutamate concentration ([Glu]o) in rat cortical synaptosomes in vitro. There was a decrease and increase of the [Glu]o at high and low Na+ concentrations, respectively, in a Ca2+-free medium. The changes in [Glu]o in both directions were temperature-sensitive, and reversed at around 30mM of Na+. Dihydrokainate (DHK), a non-transportable inhibitor selective for glial glutamate transporter GLT-1, suppressed the decrease in [Glu]o, and the reversal of [Glu]o change was shifted to about 60 mM Na+. There was no change in the maximum [Glu]o at total Na+ substitution. Further pharmacological analysis revealed that D-aspartate and DL-threo-β-hydroxy-aspartate (THA), transportable substrates of glutamate transporters, increased the [Glu] o in standard media. In contrast, β-phenylglutamic acid, a structural analogue of glutamate, suppressed both the decrease in [Glu] o in standard medium and the increase in [Glu]o in low Na+ medium. It is, thus, concluded that both the direction and the amount of [Glu]o changes are determined by a balance of the uptake and reversed transport of glutamate, and that this assay system is suitable for evaluation of the effect of this on glutamate transporters.

    Original languageEnglish
    Pages (from-to)813-816
    Number of pages4
    JournalBiological and Pharmaceutical Bulletin
    Issue number6
    Publication statusPublished - 2004 Jun


    • DL-threo-β-hydroxy-aspartate
    • Dihydrokainate
    • Glutamate reversed transport
    • Glutamate transporter
    • Glutamate uptake
    • Synaptosome

    ASJC Scopus subject areas

    • Pharmacology
    • Pharmaceutical Science


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