The alteration of extracellular sodium and potassium ionic activities of hippocampal neurons in epileptiform rats kindled by coriaria lactone

AIM and METHODS: The sodium ion Na⁺ and potassium ion K⁺ selective microelectrodes were used to measure changes of ionic activity of extracellular sodium and potassium( Na⁺]_o, K⁺]_o) in hippocampus and hippocampal slice during epieptic seizure induced by intrahippocampal microinjection of coriaria lactone(CL) in rats and perfusing hippocampal slice with CL. RESULTS:30 s, 1min and 2min after injection of CL into hippocampus, the Na⁺]_o decreased 27.7 mmol/L, 50.3 mmol/L, 57.8 mmol/L respectively and the K⁺]_o increased 2.3 mmol/L, 2.4 mmol/L, 2.9 mmol/L respectively compared with control values(P＜0.01). The K⁺]_o returned to the control level 3min after local application of CL, but theNa⁺] _o was still lower than that of control group(P＜0.01). The Na⁺]_o and the K⁺]_o were measured also in hippocampal silces and results are similar to those of experiments in vivo. CONCLUSION: The influx of Na⁺and the flux of K⁺occurred during epileptiform discharges of hippocampal neurons induced by administration of CL.