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

The release of [3H]gamma-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 gamma-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 microM) 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 gamma-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.