ATTENUATION OF A VOLTAGE-DEPENDENT SODIUM CURRENT BY GABA (IDENTIFIEDNEURONS, 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 tetrodot oxin to the bath medium abolished the voltage dependent inward current . This voltage dependent sodium current was reduced with GABA applicat ion. Muscimol exerted the same effect as GABA whereas administration o f baclofen had no effect. Voltage-dependent sodium and calcium current s of the neurons B1-B3 remained unchanged with GABA application. It is concluded that GABA is capable of reducing voltage-dependent sodium c urrents of distinct neuronal individuals via a GABA(A) receptor-like s tructure.