马桑内酯致痫大鼠海马神经细胞外Na^+、K^+活度的变化

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

目的和方法 :应用Na+、K+选择性微电极检测马桑内酯致痫大鼠海马及海马脑片神经细胞外Na+、K+活度的改变。结果 :海马内注射马桑内酯 (5 μL ,5× 10 -4 mol/L)致痫大鼠 30s、1min和 2min后 ,海马神经细胞外Na+活度分别低于对照组 2 7 7mmol/L、5 0 3mmol/L和 5 7 8mmol/L ,而K+活度则分别高于对照组 2 3mmol/L、2 4mmol/L和 2 9mmol/L(P <0 0 1)。 3min后 ,K+活度基本恢复至对照水平 ,而Na+活度仍持续低于对照水平 (P <0 0 1)。海马脑片的实验结果与在体实验相似。结论 :海马神经细胞处于癫痫状态时 ,存在Na+内流、K+外流现象。

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 the [Na +] 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.