Abe K, Abe Y, Saito H
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, The University of Tokyo, Japan.
Biol Pharm Bull. 2000 Feb;23(2):204-7. doi: 10.1248/bpb.23.204.
Astrocytes have a function in the uptake of excitatory neurotransmitter L-glutamate via the glutamate transporter. To evaluate the L-glutamate clearance capacity of astrocytes, we developed a colorimetric method for the determination of L-glutamate concentration and measured changes in extracellular L-glutamate concentration in rat cortical astrocyte cultures. When L-glutamate (50-200 microM) was added to astrocyte cultures and incubated for 1-8 h, the extracellular L-glutamate concentration declined with time. When L-glutamate was mixed with astrocyte culture supernatants only, no significant change in L-glutamate concentration was observed, ruling out the possibility that L-glutamate is spontaneously or enzymatically degraded in the extracellular space. Alternatively, the time-dependent decline of extracellular L-glutamate concentration was blocked by the presence of glutamate uptake inhibitors, indicating that the glutamate uptake system of astrocytes plays a major role in the clearance of extracellular L-glutamate.
星形胶质细胞通过谷氨酸转运体发挥摄取兴奋性神经递质L-谷氨酸的功能。为了评估星形胶质细胞对L-谷氨酸的清除能力，我们开发了一种比色法来测定L-谷氨酸浓度，并测量大鼠皮质星形胶质细胞培养物中细胞外L-谷氨酸浓度的变化。当向星形胶质细胞培养物中加入L-谷氨酸（50 - 200微摩尔）并孵育1 - 8小时时，细胞外L-谷氨酸浓度随时间下降。当仅将L-谷氨酸与星形胶质细胞培养上清液混合时，未观察到L-谷氨酸浓度有显著变化，排除了L-谷氨酸在细胞外空间自发或酶促降解的可能性。另外，细胞外L-谷氨酸浓度随时间的下降被谷氨酸摄取抑制剂的存在所阻断，表明星形胶质细胞的谷氨酸摄取系统在清除细胞外L-谷氨酸中起主要作用。
