Net uptake of gamma-aminobutyric acid by a high-affinity system of rat brain synaptosomes.

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Abstract
Rat brain synaptosomes isolated on discontinuous Ficoll gradient carry out rapid net uptake of GABA through a high-affinity system (Km = 6.25 .mu.M; Vmax = 1.2 nmol/min per mg of protein). The uptake of the labeled neurotransmitter is dependent on Na concentration and is abolished by addition of 40 .mu.M veratridine or 0.5 mM 2,4-diaminobutyric acid. Homoexchange in this preparation accounts for less than 10% of the measured uptake of [14C]GABA. The high-affinity transport apparently exhibits properties characteristic of a system that is responsible for the rapid removal of GABA acid from the synaptic cleft after neuronal transmission.