Effects of the hypnotic drug etomidate in a model nervous system (Buccal ganglia, Helix pomatia).

1. Effects of the hypnotic drug etomidate were studied with intracellular recordings of the identified neurons B1 to B4 of the buccal ganglia of Helix pomatia. 2. At threshold doses of 10 mumol/l, etomidate mainly affected interneuronal networks. 3. In concentrations above 200 mumol/l, the drug induced typical epileptic activities (paroxysmal depolarization shifts, PDS). Neurons B1 to B4 generated epileptic activities in differential concentration ranges. PDS were synchronized via electrical contacts. PDS could be blocked by the "calcium antagonist" verapamil but not by a block of chemical synaptic transmission. 4. In comparison with the epileptogenic drug pentylenetrazol, effective doses of etomidate to induce PDS were about 100 times lower.