Endogenous GABA release from slices of rat cerebral cortex and hippocampus in vitro

Using a rapid, simple and sensitive radioreceptor assay, a Ca2+-dependent K+-evoked release of endogenous GABA was demonstrated from rat cortical and hippocampal slices in vitro. This evoked-release of endogenous GABA was similar to that of [3H]GABA release (in its Ca2+ dependency) but differed from the latter in having a higher signal to noise level. Neither 5-HT nor a stable enkephalin analogue had any effect on endogenous GABA release from hippocampus slices.