Lidocaine depresses synaptic activity in the rat hippocampal slice

The direct effect of the local anesthetic lidocaine was studied using the hippocampal slice preparation in order to assess the involvement of this structure in lidocaine-induced seizure activity. Changes in the evoked field potential amplitude and latency were used to measure the effect of the drug. A dose-dependent depression of the evoked field potentials was observed at lidocaine concentration of 10(-4)M and greater. No synchronized population bursting (seizures) was observed at any of the concentrations tested (10(-6)M to 10(-3)M). However, the hippocampal slice preparation is capable of producing seizure activity, as was demonstrated following application of penicillin G. The results suggest that the hippocampus is not the site of lidocaine-induced seizure activity.