Attenuation of a voltage-dependent sodium current by GABA (identified neurons, buccal ganglia, Helix pomatia).

The action of systemically applied GABA on voltage-dependent currents of the identified neurons B1-B4 in the buccal ganglia of Helix pomatia were investigated by conventional voltage clamp techniques. In the B4 neuron, superfusion with sodium-free solution or addition of tetrodotoxin to the bath medium abolished the voltage dependent inward current. This voltage dependent sodium current was reduced with GABA application. Muscimol exerted the same effect as GABA whereas administration of baclofen had no effect. Voltage-dependent sodium and calcium currents of the neurons B1-B3 remained unchanged with GABA application. It is concluded that GABA is capable of reducing voltage-dependent sodium currents of distinct neuronal individuals via a GABAA receptor-like structure.