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B.A. Daniels, W.H. Baldridge; Effects of Nitric Oxide Synthase Inhibition on Goldfish Horizontal Cell Light Adaptation . Invest. Ophthalmol. Vis. Sci. 2005;46(13):602.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Exposure of isolated teleost retina to bright background illumination ("light–adaptation") reduces the receptive–field size of horizontal cells. Although nitric oxide has the capacity to uncouple horizontal cells, and has been implicated in some aspects of light–adaptation in the retina, it has not been demonstrated directly that endogenous nitric oxide reduces horizontal cell receptive field size during light–adaptation. Therefore, we have investigated the effects of a nitric oxide synthase inhibitor on goldfish horizontal cell light–adaptation. Methods: An isolated goldfish retina preparation was used and the light–evoked responses of horizontal cells measured using intracellular recording. The receptive–field size of horizontal cells was assessed by translating a 250 µm slit across the retina and by comparing the responses elicted by an annulus (5 mm outer diameter, 3.75 mm inner diameter) to those produced by a spot (2.5 mm diameter). The responses of horizontal cells were assessed before and after exposure to bright full–field illumination in the presence or absence of the nitric oxide synthase inhibitor NG–nitro–L–arginine methyl ester (L–NAME). Results: Following bright background illumination the decrease in the response of horizontal cells as a function of slit stimulus translation distance increased. For example, prior to illumination, both in the presence or absence of 100 µM L–NAME, the response to the slit 2.0 mm distant from the impaled cell was typically 70% less than the response at the center. Following illumination, the relative response at this distance was even less, decreasing by 80% compared to the response at the center. However, in the presence of L–NAME, illumination did not decrease the response at 2.0 mm (69%). Similar results were found using an annulus stimulus. Prior to illumination, both in the presence or absence of L–NAME, the response to the annulus was similar to the response to the spot. After illumination the annulus response was decreased by 25% compared to the spot. In the presence of L–NAME the response to the annulus was not decreased by illumination. Conclusions: The inhibitor of nitric oxide synthase, L–NAME, blocked the effect of bright illumination on horizontal cell receptive–field size. This suggests that nitric oxide contributes to the decrease of horizontal cell receptive field–size after light–adaptation.
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