NMDA-responsible, APV-insensitive receptor in cultured human astrocytes.
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.
Department of Neurosurgery, Kobe University School of Medicine, Japan.
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Kondoh
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Nishizaki
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Aihara
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Tamaki
D001253:Astrocytes / Q000187:drug effects* / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D019204:GTP-Binding Proteins / Q000502:physiology; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D005998:Glycine / Q000494:pharmacology; D006801:Humans; D016202:N-Methylaspartate / Q000494:pharmacology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects*; D014633:Valine / Q000031:analogs & derivatives* / Q000494:pharmacology*
D005904:Glial Fibrillary Acidic Protein; D016194:Receptors, N-Methyl-D-Aspartate; D016202:N-Methylaspartate; C056639:2-amino-5-phosphopentanoic acid; D019204:GTP-Binding Proteins; D014633:Valine; D002118:Calcium; D005998:Glycine