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Gabriel Peinado, Kaitryn E. Ronning, Rolf Herrmann, Marie E Burns, Edward N Pugh; Genetic dissection of rod and cone contributions to the ERG in the living mouse. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3182.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the dynamic operating range of rod and cone photoreceptors in vivo and better understand the contribution of the two photoreceptor classes to ERG a- and b- waves
Mice were dark adapted overnight and anesthetized with 2% isofluorane; electroretinograms (ERGs) were recorded with a Phoenix Labs Maxwellian view system using 1 ms UV (360 nm) and green (510 nm) LED stimulation. Responses were recorded in the dark adapted eye, and in the presence of backgrounds whose intensity spanned 8 orders of magnitude. Wild type, GNAT1-/- (no rod function) and GNAT2-/- (no cone function) animals, and spectral sensitivity data were used to assess the relative contributions of rods and cones to saturating a-waves, and to b-waves
The dark-adapted a-wave intensity-response function exhibited two distinct components, but both components were ascribable to rods based on their relative sensitivities to green and UV light and their presence in Gnat2-/- mice. The UV/green sensitivity ratio switched from rod to cone domination as background intensities increased. Using Gnat1-/- and Gnat2-/- mice, we identified a range of intermediate background intensities over which the b-wave was dominated by cone signaling yet the a-wave remained dominated by rod signaling.
The ERG a-wave arises predominantly from rods, even in the presence of relatively intense backgrounds, owing to the sheer numerosity of the rods in the mouse retina; a major component often attributed to cones arises from rods. Nonetheless, the b-wave, which is known to arise primarily from ON- bipolar cells, is driven predominantly by cones even when rods generate large a-waves and thus clearly are not saturated. These results corroborate and extend previous studies of rod and cone vision in mice (Naarendorp and others, 2010) and recent analysis of the rod-driven ERG a-wave (Robson and Frishman, 2014).
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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