Gamma-aminobutyric acid release from neurons and glia

Release of 3H-GABA into the medium from bulk-isolated glial cells, neuronal perikarya and synaptosomes has been studied, using a continuous perfusion system. The fractions were incubated with 3H-GABA and spontaneous efflux of label in the presence and absence of aminooxyacetic acid (AOAA) was recorded. Unlabelled GABA at micromolar concentrations markedly stimulated 3H-GABA efflux from glia, synaptosomes and neurons. 3H-GABA from all fractions was also markedly sensitive to stimulation by ouabain. Glutamate was effective in stimulating the spontaneous efflux in the presence of AOAA, while superfusion with a calcium-deprived medium only slightly stimulated the 3H-GABA efflux from neurons and glia.