An arthropod NMDA receptor.
Identified crayfish visual interneurons respond to illumination with a compound EPSP of up to 40 mV. L-glutamate, quisqualate, and kainate mimic the depolarizing action of the natural transmitter. In reduced Mg2+, N-methyl-D-aspartate (NMDA) elicits a depolarization with a reversal potential (Erev) = -60 mV. Erev is independent of extracellular calcium but shifts to +4 mV if potassium conductances are blocked by intracellular CS+. The results suggest that NMDA may gate more than one class of ionic channel. The NMDA-elicited response is enhanced and prolonged by glycine, and kynurenate competitively blocks the action of glycine. The NMDA antagonist, D-AP7, selectively blocks the NMDA response while enhancing the EPSP. The actions of NMDA are consistent with a role in the neural mechanisms of visual adaptation. This is the first description of an NMDA receptor in an invertebrate.
Pfeiffer-Linn
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Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251.
Glantz
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RM
D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives*; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D003400:Astacoidea; D002586:Cesium / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D005971:Glutamates / Q000032:analysis / Q000494:pharmacology; D018698:Glutamic Acid; D005998:Glycine / Q000494:pharmacology; D007124:Immunoenzyme Techniques; D007395:Interneurons / Q000187:drug effects / Q000502:physiology*; D007736:Kynurenic Acid / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D016202:N-Methylaspartate / Q000494:pharmacology*; D010775:Photic Stimulation; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D014785:Vision, Ocular; D005680:gamma-Aminobutyric Acid / Q000032:analysis / Q000502:physiology
D000596:Amino Acids; D005971:Glutamates; D016194:Receptors, N-Methyl-D-Aspartate; D002586:Cesium; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; D007736:Kynurenic Acid; D008274:Magnesium; C031231:2-amino-7-phosphonoheptanoic acid; D005998:Glycine