[Shifts in the steady potential and intracellular concentration of potassium in the cerebral cortex in response to prolonged low-frequency electrical stimulation of the surface of the cortex in the rat].

Cyclic discharges occurring during prolonged low-frequency electric stimulation of the cortical surface were studied in the rat neocortex by means of K+ selective microelectrodes. Duration of excitation cycles and intervals between them depended on the parameters of stimulation. Surface potential shift reached 4-5 mV and [K+]0 increased to 8-10 mM. The cyclic excitation process was not self-sustained and stopped just after the current was switched off. Small doses of nembutal (10-20 mg/kg) increased both the threshold for the cyclic process onset and duration of the intervals between the active phases. Higher nembutal doses (30-40 mg/kg) abolished cyclic excitation for 2-3 hours. This model of cyclic discharges is supposed to be useful for investigation of the mechanism of seizure activity and of the effect of antiepileptic drugs.