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Q Zeng, J Stone, DG McMahon; Functional Determinants of Ion Flow through Retinal GluR1 Receptor Channels . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4755.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To characterize the properties of a GluR1 glutamate receptor subunit homologue cloned from hybrid striped bass retina, functional receptors were heterologously expressed in cultured HEK 293 cells. Methods:Experiments were performed on cells co-transfected with GluR1and GFP cDNAs via calcium phosphate 48-72 hours after transfection. Receptor-expressing cells were identified by fluorescence and recorded in the whole-cell voltage-clamp configuration. Results:Slow application of 1 mM glutamate did not evoke steady-state currents in GFP-cells, whereas co-application of 1 mM glutamate with 30 µM cyclothiazide (CTZ), a AMPA receptor desensitization inhibitor, produced an inward current of 23 ± 3 pA (n= 16, mean ± SE) at a holding potential of -60 mV. The inward currents induced by glutamate plus CTZ were completely blocked by 100 µM GYKI-52466, a AMPA receptor blocker. Glutamate plus CTZ did not induce any currents in non-transfected cells (n=8). In addition, current-voltage (I-V) relations of glutamate-induced currents in the presence of CTZ displayed a strong outwardly rectifying property with a reversal potential of 0 mV(n=8). Co-application of zinc (0.1-1mM) significantly reduced receptor mediated currents with a voltage independent manner (n=5). Conclusion:Homomeric GluR1 channels from the hybrid striped bass retina show both similarities and differences to the functional properties of mammalian GluR1. The rectifying I-V relation differs while the suppression by zinc is similar.
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