Epileptiform activity induction with electrolyte imbalance in brain slices: mechanisms involved in control

Epilepsy is a disorder of recurrent seizure activity caused by rhythmic firing of neurons. Epileptiform activity can be generated by incubating brain slices in magnesium-free artificial cerebrospinal fluid (ACSF). In the present study, epileptiform discharges induced by the omission of magnesium ions from ACSF has been studied in hippocampal slices obtained from young rats using patch clamp tight-seal whole cell recording technique. Effects of AP5 to block NMDA receptor activation and acidic pH shift of ACSF on the epileptiform current was studied. It was found that magnesium-free ACSF induced epileptiform activity frequency was attenuated with AP5 application more than 50 %. The pH shift of the magnesium-free ACSF from 7.3 to 7.1 depressed the epileptiform activity. Both effects were shown to be reversible. According to the results of this study, epileptiform activity and mild extracellular acidic shifts do not interact to aggravate excitability conditions in CA1 pyramidal neurons.