Potassium-stimulated gamma-aminobutyric acid release from neurons and glia.

Potassium-stimulated [3H]GABA release has been studied with fractions of glial cells, neuronal perikarya and synaptosomes using a superfusion technique. A monotonic increase in the [3H]GABA release was observed when external K+ concentration was raised from 5 to 15 mM. However, there was no further increase in the [3H]GABA release when K+ was raised above 15 mM. The KCl-stimulated release was saturable at the level of 60-100% stimulation. Potassium-stimulated [3H]GABA release from glial cells was unchanged in the absence of calcium while release from synaptosomes and neuronal perikarya demonstrated Ca2+-dependence. The potassium-stimulated [3H]GABA release was enhanced when superfusion was performed in the presence of 10(-5) M ouabain.