Effects of the γ-aminobutyrate transaminase inhibitors gabaculine and γ-vinyl GABA on γ-aminobutyric acid release from slices of rat cerebral cortex

Abstract

The release of [³H]γ-aminobutyric acid (GABA) from pre-loaded slices of rat cerebral cortex was investigated in the presence and absence of the GABA-transaminase inhibitors gabaculine and γ-vinyl GABA. In the experiments carried out without an inhibitor, an ion-exchange column chromatographic technique was used to separate [³H]GABA from tritiated metabolites released with it into the superfusate. The presence of gabaculine (5 μM) substantially reduced the Ca²⁺-dependence of the release of [³H]GABA evoked by a 4 min 30 mM K⁺ pulse, whereas this was not appreciably reduced by the presence of γ-vinyl GABA (2 mM or 10 mM). Nevertheless, the characteristics of [³H]GABA release were not identical in the presence and absence of either inhibitor.