Interactions of the imidazodiazepine Ro 15-4513 with chemical convulsants.

1. The proconvulsant effects of the imidazodiazepine Ro 15-4513, were investigated in mice by use of intravenous infusion of a variety of convulsant drugs. 2. Dose-response and time course studies of Ro 15-4513 against gamma-aminobutyric acid (GABA) antagonists were performed. On the basis of these studies a maximally effective dose of 5 mg kg-1 was administered 5 min before the determination of seizure thresholds in subsequent experiments. 3. Ro 15-4513 (5 mg kg-1) significantly lowered seizure thresholds to pentylenetetrazole, bicuculline and the convulsant benzodiazepine Ro 5-3663, but failed to alter seizure thresholds to picrotoxin, strychnine, caffeine and quipazine. 4. Ro 15-4513 significantly raised seizure threshold to the benzodiazepine receptor inverse agonist methyl 6,7-dimethoxy-4 ethyl-beta-carboline-3-carboxylate (DMCM). 5. These results are discussed in relation to other studies investigating the proconvulsant and alcohol-antagonizing effects of Ro 15-4513.