Kondoh T, Nishizaki T, Aihara H, Tamaki N
Department of Neurosurgery, Kobe University School of Medicine, Japan.
Life Sci. 2001 Mar 2;68(15):1761-7. doi: 10.1016/s0024-3205(01)00971-7.
The present study was conducted to assess N-methyl-D-aspartate (NMDA)-responsible receptors in cultured human astrocytes by monitoring whole-cell membrane currents. NMDA generated currents, that are potentiated by glycine and blocked by Mg2+, with the current/voltage relation showing a reversal potential of +/- 0 mV. The currents were not inhibited by either the selective NMDA receptor antagonist, D-2-amino-5-phosphonovaleric acid (APV), or the non-selective ionotropic glutamate receptor antagonist, kynurenic acid. The currents were inhibited only by 19% in Ca2+-free extracellular solution. Furthermore, GDPbetaS, a broad G-protein inhibitor, inhibited NMDA-induced currents to 82% of original levels. The results of the present study thus suggest that an NMDA-responsible, APV-insensitive receptor with low Ca2+ permeability, distinct from the neuronal NMDA receptors, is expressed in human astrocytes and that the receptor is regulated in part by an unknown G-protein-linked receptor.
本研究旨在通过监测全细胞膜电流来评估培养的人星形胶质细胞中与N-甲基-D-天冬氨酸（NMDA）相关的受体。NMDA产生的电流可被甘氨酸增强并被Mg2+阻断，电流/电压关系显示反转电位为+/- 0 mV。这些电流既不被选择性NMDA受体拮抗剂D-2-氨基-5-磷酸戊酸（APV）抑制，也不被非选择性离子型谷氨酸受体拮抗剂犬尿烯酸抑制。在无Ca2+的细胞外溶液中，电流仅被抑制19%。此外，一种广泛的G蛋白抑制剂GDPβS可将NMDA诱导的电流抑制至原始水平的82%。因此，本研究结果表明，人星形胶质细胞中表达了一种与NMDA相关、对APV不敏感、Ca2+通透性低的受体，该受体不同于神经元NMDA受体，且该受体部分受未知的G蛋白偶联受体调节。
