Bradford H F, Young A M, Crowder J M
Department of Biochemistry, Imperial College of Science and Technology, London, U.K.
Neurosci Lett. 1987 Oct 29;81(3):296-302. doi: 10.1016/0304-3940(87)90399-5.
The glutamate (and aspartate) uptake blocker threo-3-hydroxyaspartate (20 microM) was added to superfusion fluids employed for in vivo microdialysis of corpus striatum, and to incubation medium for striatal slices (5 microM). In vivo it caused an increase in glutamate and aspartate concentrations in the superfusion fluid. In vitro it caused increases in the levels of glutamate, aspartate, GABA, taurine and glutamine in the incubation fluid. Tetrodotoxin (1 microM) did not influence the rises in glutamate or aspartate. It is concluded from these results that there is a continuous outward leakage of glutamate, and aspartate, from neural cells which is normally balanced by an inward flux due to reuptake processes. This leakage is distinct from synaptic release of these substances due to spike activity, since tetrodotoxin added to striatal slices did not diminish the action of threo-3-hydroxyaspartate. The significance of the findings for mechanisms leading to ischaemic or hypoxic brain damage, and basic mechanisms in epilepsy is discussed.
将谷氨酸（和天冬氨酸）摄取阻断剂苏-3-羟基天冬氨酸（20微摩尔）添加到用于纹状体体内微透析的灌流液中，以及添加到纹状体切片的孵育培养基中（5微摩尔）。在体内，它导致灌流液中谷氨酸和天冬氨酸浓度增加。在体外，它导致孵育液中谷氨酸、天冬氨酸、γ-氨基丁酸、牛磺酸和谷氨酰胺水平升高。河豚毒素（1微摩尔）不影响谷氨酸或天冬氨酸的升高。从这些结果可以得出结论，神经细胞存在谷氨酸和天冬氨酸的持续外向泄漏，由于再摄取过程，这种泄漏通常由内向通量平衡。这种泄漏不同于由于锋电位活动导致的这些物质的突触释放，因为添加到纹状体切片中的河豚毒素并没有减弱苏-3-羟基天冬氨酸的作用。讨论了这些发现对于导致缺血性或缺氧性脑损伤的机制以及癫痫的基本机制的意义。
