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 μM 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 μM 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.
Key WordsGlutamate GABA NMDA synaptosomes
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