Non-NMDA type excitatory amino acid receptors mediate rod input to horizontal cells in the isolated rat retina.
The actions of excitatory amino acid agonists and antagonists on rod driven horizontal cells were studied in the isolated retina of the rat. Horizontal cells were depolarised by L-glutamate, kainate and quisqualate but not by N-methyl-D-aspartate (NMDA). The broad band excitatory amino acid antagonist, kynurenate and the non-NMDA antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), hyperpolarised horizontal cells, blocking the light responses and also the effects of agonists. In contrast, the competitive NMDA antagonists, 3-[(+/-)-2-carboxypiperazin-4-yl]-propyl-1-phosphonate (CPP) and 2-amino-5-phosphono-pentanoate (AP5) were without effect. Thus, rat horizontal cells possess excitatory amino acid receptors of the non-NMDA type and these mediate their rod driven inputs.
Vision Research Unit, Sherrington School, U.M.D.S., Rayne Institute, St Thomas' Hospital, London, U.K.
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Hankins
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Ikeda
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D003623:Dark Adaptation; D008564:Membrane Potentials / Q000187:drug effects; D016202:N-Methylaspartate / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D010786:Photoreceptor Cells / Q000502:physiology*; D010879:Piperazines / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017459:Receptors, Amino Acid / Q000502:physiology*
D000596:Amino Acids; D010879:Piperazines; D011810:Quinoxalines; D017459:Receptors, Amino Acid; C065286:SDZ EAA 494; D016202:N-Methylaspartate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione