Lisý V, Stastný F
Institute of Physiology, Academy of Sciences, Prague, Czech Republic.
Neurosci Lett. 1993 Aug 6;158(1):113-6. doi: 10.1016/0304-3940(93)90625-u.
Na(+)-dependent binding of L-glutamate in cortical and hippocampal synaptic membranes from hyperammonemic rats was compared to corresponding data in the controls. In hippocampal membranes, repeated hyperammonemia resulted in a 13% and 18% decrease in binding in 20-day-old and 50-day-old rats, respectively. The decrease was statistically significant (P < 0.05) in the older animals and Scatchard analysis revealed a 19% reduction in the number of binding sites without any changes in the affinity. Within the hippocampal formation, the binding in the dentate gyrus was the most sensitive to hyperammonemia where a 21% decrease was found (P < 0.01), whilst the decline of binding in CA1 and CA3 areas of the hippocampus proper was not significant. The results support the idea that excessive accumulation of extracellular glutamate during hyperammonemia is a consequence not only of its increased release, but also of the blocking of Na(+)-dependent binding of glutamate to specific uptake sites.
将高血氨大鼠皮质和海马突触膜中L-谷氨酸的钠依赖性结合与对照组的相应数据进行比较。在海马膜中，反复高血氨分别导致20日龄和50日龄大鼠的结合减少13%和18%。在老年动物中，这种减少具有统计学意义（P<0.05），Scatchard分析显示结合位点数量减少19%，而亲和力无任何变化。在海马结构中，齿状回的结合对高血氨最为敏感，减少了21%（P<0.01），而海马体CA1和CA3区的结合下降不显著。这些结果支持了这样一种观点，即高血氨期间细胞外谷氨酸的过度积累不仅是其释放增加的结果，也是谷氨酸钠依赖性结合到特定摄取位点受阻的结果。
