April 2011
Volume 52, Issue 14
ARVO Annual Meeting Abstract  |   April 2011
Bleaching Adaptation in a Mammalian Photoreceptor
Author Affiliations & Notes
  • Michael L. Woodruff
    Integrative Biology and Physiology, Univ of California, Los Angeles, Los Angeles, California
  • Carter Cornwall
    Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts
  • Gordon L. Fain
    Integrative Biology and Physiology, Univ of California, Los Angeles, Los Angeles, California
    Jules Stein Eye Institute and Department of Ophthalmology, UCLA, Los Angeles, California
  • Footnotes
    Commercial Relationships  Michael L. Woodruff, None; Carter Cornwall, None; Gordon L. Fain, None
  • Footnotes
    Support  NIH Grants EY01157 (M.C.C.) and EY01844 (G.L.F.)
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 1174. doi:
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      Michael L. Woodruff, Carter Cornwall, Gordon L. Fain; Bleaching Adaptation in a Mammalian Photoreceptor. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1174.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : We developed a method to record from isolated rods whose pigment has been bleached over a much wider range than previously possible, and whose pigment is regenerated with exogenous 11-cis retinal. We have used this method to examine the physiology of bleached and regenerated rods from a mammalian retina.

Methods: : We made conventional suction-electrode recordings from isolated wild-type mouse rods. In initial experiments, large bleaches produced irreversible desensitization and cell death. Successful recordings could however be obtained over bleaches as great as 90% of the total rhodopsin if (1) we included 0.1% BSA in the perfusing medium, (2) illuminated over a prolonged period with a light intensity that bleached no more that 0.2% of the pigment per second, and (3) waited as long as 60 min after the bleach for the rods to come to steady state. Pigment was regenerated by adding lipid vesicles containing 11-cis retinal. The amount of the bleach was estimated from the previously determined in vitro photosensitivity of mouse rods.

Results: : Isolated rods at steady-state after bleaching showed a reduction in circulating current, sensitivity, and time constant of recovery (tau_REC), which all decreased monotonically with the extent of the bleach. Regeneration with 11-cis retinal produced a nearly complete recovery of the amplitude, sensitivity, and waveform of the response. The decrease in sensitivity could be predicted from a simple model in which bleaching light reduced quantum catch and created a photopigment intermediate, probably opsin, which activates the visual cascade in proportion to the amount of bleached pigment and generates an equivalent background light.

Conclusions: : Our experiments show that it is possible to recreate the visual cycle in vitro. This advance will make it possible for us to study bleaching adaptation in a mammalian photoreceptor in greater detail than was previously possible, and to study the effect of introducing exogenous chromophore analogues into wild-type photoreceptors.

Keywords: photoreceptors • retina • regeneration 

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