gamma-Aminobutyric acid partly mediates the pentobarbitone depression of synaptic excitation in the guinea-pig olfactory cortex in vitro.

Pentobarbitone depresses synaptic excitation in the guinea-pig olfactory cortex slice in vitro. A study has been made to elucidate the possible role of gamma-aminobutyric acid (GABA) in this depression by testing pentobarbitone in the presence of high concentrations of the GABA blockers, i.e. picrotoxin or bicuculline. These blockers reduced the action of pentobarbitone; the dose-depression curve for pentobarbitone was shifted to the right by a factor of 2.3. It is concluded that pentobarbitone has a bimodal action, one action via GABA and another unrelated to GABA or Cl- conductances.