Presynaptic modulation of amino acid release from synaptosomes.
Using synaptosomes prepared from whole rat brain, the spontaneous, calcium-independent, and calcium-dependent release of glutamate and GABA was assessed. Time intervals of 1-30 seconds were studied. Spontaneous release of glutamate (but not GABA) was elevated by 10 microM NMDA or AMPA by thirty seconds. This stimulation was partially calcium-dependent. Calcium-dependent release induced by 30 mM KCl was biphasic, confirming previous findings. This release was stimulated at all time periods by the presence of 10 microM NMDA or AMPA in an antagonist-sensitive manner. These data suggest that glutamate and GABA are released from vesicular stores in rat synaptosomes and that some of this release is modulated by presynaptic glutamate receptors.
Department of Psychiatry, College of Medicine, University of Iowa, Iowa City 52242.
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Sherman
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Hegwood
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Baruah
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Waziri
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D007051:Ibotenic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000502:physiology*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D000596:Amino Acids; D005971:Glutamates; D011810:Quinoxalines; D007051:Ibotenic Acid; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; C056723:FG 9041; D016202:N-Methylaspartate; D011189:Potassium Chloride; D015763:2-Amino-5-phosphonovalerate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D002118:Calcium