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Comparison of the Properties of γ‐Aminobutyric Acid and L‐Glutamate Uptake into Synaptic Vesicles Isolated from Rat Brain
Author(s) -
Fykse Else M.,
Christensen Hege,
Fonnum Frode
Publication year - 1989
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.1471-4159.1989.tb02546.x
Subject(s) - nigericin , glutamate receptor , valinomycin , synaptic vesicle , vesicle , chemistry , biophysics , biochemistry , protonophore , glutamic acid , biology , amino acid , membrane potential , membrane , receptor
Rat brain synaptic vesicles exhibit ATP‐dependent uptake of γ‐[ 3 H]amino‐ n ‐butyric acid ([ 3 H]GABA) and l ‐[ 3 H]glutamate. After hypotonic shock, the highest specific activities of uptake of both l ‐glutamate and GABA were recovered in the 0.4 M fraction of a sucrose gradient. The uptakes of l ‐glutamate and GABA were inhibited by similar, but not identical, concentrations of the mitochondrial uncoupler carbonyl cyanide m ‐chlorophenylhydrazone and the ionophores nigericin and gramicidin, but they were not inhibited by the K + carrier valinomycin. N, N′ ‐Dicyclohexyl‐carbodiimide and N ‐ethylmaleimide, Mg 2+ ‐ATPase inhibitors, inhibited the GABA and L‐glutamate uptakes similarly. Low concentrations of CI − stimulated the vesicular uptake of l ‐glutamate but not that of GABA. The uptakes of both l ‐glutamate and GABA were inhibited by high concentrations of CI − . These results indicate that the vesicular GABA and l ‐glutamate uptakes are driven by an electrochemical proton gradient generated by a similar Mg 2+ ‐ATPase. The vesicular uptake mechanisms are discussed in relation to other vesicle uptake systems.