| 10077667 |
Han Y, Wu SM: Modulation of glycine receptors in retinal ganglion cells by zinc. Neuroreport. 2004 Mar 22;15(4):583-7.
Effects of zinc, an endogenous neuromodulator in the central nervous system, on glycine receptors (GlyRs) in retinal ganglion cells were investigated by using the whole-cell voltage-clamp technique. Zn2+ at low concentration (<2 microM) potentiated the glycine-induced chloride current and at higher concentration (> 10 microM) suppressed it. This biphasic regulatory action of zinc acted selectively on the fast component of the glycine-induced current mediated by the strychnine-sensitive GlyRs, but not on the slow component mediated by the 5,7-dichlorokynurenic acid-sensitive GlyRs. Dose-response studies showed that 1 microM Zn2+ increased the maximum glycine response (I approximately) and shifted the EC50 to the left, suggesting that Zn2+ at low concentrations acts as an allosteric activator of the strychnine-sensitive GlyRs. Zn2+ at a concentration of 100 microM did not alter I approximately and shifted the EC50 to the right, indicating that Zn2+ at high concentrations acts as a competitive inhibitor of the GlyRs. Physiological functions of zinc modulation of GlyRs in retinal ganglion cells are discussed. |
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