Carbamazepine suppresses synchronized afterdischarging in disinhibited immature rat hippocampus in vitro

Bath application of therapeutic concentrations of the anticonvulsant carbamazepine suppressed penicillin-induced synchronized afterdischarging in immature rat CA₃ hippocampal pyramidal cells. Afterdischarging was completely abolished in all preparations at a concentration of 30 μM (IC₅₀ = 8.5 ± 1.4 μM; mean ± S.E.M.). The duration of the preceding epilptiform burst was not altered at this concentration and was diminished by only 24.4 ± 1.2% at a supratherapeutic concentration of 100 μM. These results suggest that a carbamazepine-sensitive neurophysiological mechanism distinct from those responsible for epileptiform burst generation plays a key role in the generation of afterdischarges in developing hippocampus.