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R.H. Hanitzsch, A. Flade, L. Küppers; The Effect of GABA and the GABA-Uptake-Blocker NO-711 on the B-Wave of the ERG and the Responses of Horizontal Cells to Light in the Isolated Rabbit Retina . Invest. Ophthalmol. Vis. Sci. 2003;44(13):5145.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The b-wave of the electroretinogram (ERG), which originates partly in on-bipolar cells, can be influenced by GABAergic horizontal cells (HCs) and GABAergic amacrine cells (ACs). To distinguish between these two influences in a mammalian retina the effects of GABA and the specific GABA-uptake-blocker NO-711, which blocks the GABA transporter GAT1 of ACs, were studied. Methods: The ERG and the intracellular responses of HCs to light were recorded in the isolated superfused rabbit retina. GABA and NO-711 were added separately to the superfusate. Light stimuli were diffuse white light (log 0=38Wm-2) of increasing intensity. Results: NO-711 enlarged the b-wave of the ERG significantly; the maximal increase was obtained for light intensities -5 log units (197±63% SD, n=9, p=0.0096, Wilcoxon signed rank test) and -4.5 log units (199±62% SD, n=5). NO-711, however, had no effect on the light responses of HCs. GABA reduced both the light responses of HCs and the b-wave of the ERG. 2mM GABA reduced the responses of HCs at a light intensity -5 log units to 57±25% and at -4 log units to 52±16% (SD, n=7, p=0.014, Wilcoxon signed rank test). With 1mM GABA at -4 log units intensity the reduction of the b-wave was to 65±10% (SD, n=9, p=0.002, Wilcoxon signed rank test). Conclusions: These results indicate that, in some circumstances at least, the GABAergic influences of HCs and ACs upon the b-wave may oppose each other.
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