Surface charge impact in nonsynaptic model of epilepsy in rat hippocampus.

Decreasing of surface charge screening near voltage-gated ion channels via reduction of extracellular cation divalent ions provide potent mechanism of altering cellular excitability and seizure threshold. Spontaneous field potentials were recorded from horizontal brain slices of young Wistar rats (postnatal day 10-12). Extracellular registrations wereobtained from CA1 and CA3 area of hippocampus. For induction of nonsynaptic epileptiform activity slices were perfused with artificial cerebrospinal fluid with omitted Ca2+and Mg2+ ions. Effect of different Mg2+ concentration (1, 2, and 3mmol/l) on initial stage of nonsynaptic epileptiform discharges was studied. Our results suggest that the change in Mg2+ concentration dramatically affects the probability of induction of low-Ca2+seizure-like activity (SLA), providing evidence that Mg2+ can alter cerebral excitability by affecting the surface charge and supporting the idea that surface charge could be a pharmacological target for anti-epileptic treatment.