Pentobarbital-like electroencephalographic rubral rhythm induced by ketamine in rabbits.

1. The effects caused by the dissociative anaesthetic drugs (PCP, KT), the sigmaopiates (SKF 10.047, cyclazocine), and the mixed excitatory amino acid antagonist CCP on the electrical activity of the red nucleus in rabbits were compared with PB. 2. Ketamine (10 mg/kg, i.v.) induced the appearance of a pentobarbital-like EEG synusoidal rhythm characterized by an increase in amplitude and a decrease in frequency of the basal electrical activity at the red nucleus level. 3. Both pentobarbital and ketamine induced rhythms were blocked by the GABA-antagonist pentylenetetrazol at the subconvulsant dose of 10 mg/kg, i.v. 4. Phencyclidine, SKF 10.047, cyclazocine, and the mixed excitatory amino acid antagonist CCP failed to affect the basal electrical activity of the red nucleus. 5. These data indicate an interaction of ketamine on the GABA neurotransmission at the level of cerebello-rubral pathways which the other PCP/sigma opiates did not present.