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Characterization of AMPA receptors on isolated amacrine‐like cells in carp retina
Author(s) -
Shen Ying,
Zhou Yu,
Yang XiongLi
Publication year - 1999
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.1999.00851.x
Subject(s) - kainate receptor , ampa receptor , glutamate receptor , nmda receptor , dnqx , chemistry , biophysics , receptor , biology , pharmacology , biochemistry
In amacrine‐like cells freshly dissociated from crucian carp (Carassius auratus) retina, we recorded whole‐cell responses to rapid application of glutamate and kainate. Currents induced by glutamate, but not kainate, usually showed extremely rapid desensitization, and the mean time constant for the decay of the responses to 10 m m glutamate was 2.77 ms. N‐methyl‐ d ‐aspartate (NMDA) failed to induce any current even with coapplication of glycine and removal of extracellular Mg 2 + · 1‐(4‐aminophenyl)‐3‐Methylcarbamyl‐4‐methyl‐7,8‐methylenedioxy‐3,4‐dihydro‐5H‐2,3‐benzodiazepine (GYKI 53655), a selective α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid (AMPA) receptor antagonist, was found to completely block glutamate‐induced currents, suggesting that the glutamate receptors on these cells are AMPA preferring. The value of EC 50 for glutamate and kainate was determined to be 2.73 m m and 97.5 μ m , respectively. Noise analysis of fluctuation of whole‐cell currents induced by kainate of different concentrations indicated that the mean conductance of the AMPA receptor channels was 5.70 pS. Splice variant analysis of the AMPA receptors was also conducted by comparing the effects of cyclothiazide, a flip receptor‐preferring modulator and 4‐[2‐(phenylsulphonylamino)ethylthio]‐2,6‐difluoro‐phenoxyacetamide (PEPA), a flop receptor‐preferring modulator, on glutamate‐induced responses. PEPA was much more potent than cyclothiazide at these receptors with a EC 50 of 17.3 μ m . The mean ratio of the potentiation by PEPA versus cyclothiazide (P/C ratio) was 4.39. These modulatory effects of cyclothiazide and PEPA were rather similar to those obtained at AMPA receptors assembled from flop variants expressed in Xenopus oocytes, suggesting that the AMPA receptor of the carp amacrine cells may predominantly consist of the flop splice variants.