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S. S. Nikonov, C. M. Craft, B. M. Brown, E. N. Pugh, Jr.; Deletion of Visual Arrestins Greatly Slows Recovery of Mouse S-Cones From Saturating Flashes. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4660.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize the functional roles of the co-expressed visual arrestins, cone arrestin (Carr) and arrestin1 (Arr1), in mouse cone phototransduction.
Carr-/-Arr1-/- double knockout (DKO) mice were created with Carr-/- mice backcrossed onto Arr1-/- background (J. Chen), verified by genotyping, and confirmed by immunohistochemistry with ARR1 (Mab D9F2), CARR (Pab LUMIj), PNA, S-, and M-opsin. Photocurrents of S-dominant cones in slices of ventral retina kept at 35 - 37oC and stimulated with 361 nm (UV) and 500 nm flashes were recorded from the perinuclear plasma membrane with suction pipettes. Rod currents were suppressed with 500 nm light.
In DKOs, visual arrestins were absent from all cones; however, in Carr-/- cones, ARR1 was expressed. The response properties of Carr-/- S-cones were not significantly different from WT. For DKO cones (n=7), the maximum recorded photocurrent was 13 pA; half-saturating flash intensity for UV light was ~ 4500 photons µm-2, close to that of WT S-cones (5000 photons µm-2, n=29); tpeak of the dim-flash response (uncorrected for a 22 ms filter delay) was 63 ms, ~10 ms faster than in WT S-cones. The amplification of DKO cones was comparable to WT cones2 (A = 4.5 s-2). The recovery of DKO cone responses was biphasic, with a fast phase comparable to that of WT cones, followed by a much slower "tail phase". For subsaturating responses the amplitude of the tail phase ranged from 0 to 50% of the total. For strongly saturating responses the initial phase of recovery was slowed increasingly with intensity, followed by a still slower tail phase, resulting in drastically slower recoveries than in WT cones.
The recovery of S-dominant murine cones from dim flashes is only modestly affected by the absence of both visual arrestins. In contrast, normal recovery from strongly saturating responses requires expression of at least one of the arrestins, but absence of CARR alone has no measurable consequence on S-cone response properties.Zhu, X, et al. IOVS 2005;46:ARVO E-Abstract 1179Nikonov et al., JGenPhysiol 2006; 127; 359-374.
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