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标题：Measurement of Glutamate Uptake and Reversed Transport by Rat Synaptosome Transporters
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作者：Atsushi Nishida ; Hiroshi Iwata ; Yukitsuka Kudo 等
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：2004
卷号：27
期号：6
页码：813-816
DOI：10.1248/bpb.27.813
出版社：The Pharmaceutical Society of Japan
摘要：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 30 m M 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 m M 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.
关键词：glutamate transporter;glutamate uptake;glutamate reversed transport;dihydrokainate; DL -threo-β-hydroxy-aspartate;synaptosome