• Benjamin J Smith, Patrice D Côté, and François Tremblay.
• Department of Biology, Dalhousie University, 1355 Oxford St., PO Box 15000, Halifax, NS, Canada B3H 4R2. Electronic address: BN948751@dal.ca.
• Neuroscience. 2016 Oct 28.

AbstractWe examined the contribution of the sodium channel isoform Nav1.8 to retinal function using the specific blocker A803467. We found that A803467 has little influence on the electroretinographic (ERG) a- and b-waves, but significantly reduces the oscillatory potentials to 40-60% of their original amplitude, with significant changes in implicit time in the rod-driven range. To date, only two cell types were found in mouse to express Nav1.8; the starburst amacrine cells (SBAC), and a subtype of retinal ganglion cells (RGC). When we recorded light responses from ganglion cells using a multielectrode array we found significant and opposing changes in two physiological groups of RGCs. ON sustained cells showed significant decreases while transient ON-OFF cells showed significant increases. The effects on ON-OFF transient cells but not ON sustained cells disappeared in the presence of an inhibitory cocktail. We have previously shown that RGCs have only a minor contribution to the oscillatory potentials (Smith et al., 2014), therefore suggesting that starburst amacrine cells might be a significant contributor to this ERG component. Targeting SBACs with the cholinergic neurotoxin ethylcholine mustard aziridinium (AF64A) caused reduction in the amplitude of the OPs similar to A803467. Our results, both using the ERG and MEA recordings from retina ganglion cells, suggest that Nav1.8 plays a role in modulating specific aspects of the retinal physiology and that SBACs are a fundamental cellular contributor to the OPs in mice, a clear demonstration of the dichotomy between ERG b-wave and oscillatory potentials.Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

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