Photoreceptor light adaptation is mediated by cytoplasmic calcium concentration

The vertebrate visual system can operate over a large range of light intensities. This is possible in part because the sensitivity of photoreceptors decreases approximately in inverse proportion to the background light intensity. This process, called photoreceptor light adaptation, is known to be me...

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Bibliographic Details
Published in:Nature (London) 1988-07, Vol.334 (6177), p.67-69
Main Authors: Matthews, H. R, Murphy, R. L. W, Fain, G. L, Lamb, T. D
Format: Article
Language:English
Subjects:
Adaptation, Ocular
Ambystoma tigrinum
Anatomy & physiology
Animals
Biochemistry
Biological and medical sciences
Calcium
Calcium - physiology
Cytoplasm - physiology
Eye and associated structures. Visual pathways and centers. Vision
Eyes & eyesight
Fundamental and applied biological sciences. Psychology
Ion Channels - physiology
Light
Light intensity
Nervous system
Photic Stimulation
Photoreception
Photoreceptor Cells - physiology
Rod Cell Outer Segment - physiology
Urodela
Vertebrates: nervous system and sense organs
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Summary:The vertebrate visual system can operate over a large range of light intensities. This is possible in part because the sensitivity of photoreceptors decreases approximately in inverse proportion to the background light intensity. This process, called photoreceptor light adaptation, is known to be mediated by a diffusible intracellular messenger, but the identity of the messenger is still unclear. There has been considerable speculation that decreased cytoplasmic Ca2+ concentration (Cai2+) may play a role in light adaptation, and recent experiments in which Ca2+ buffer was incorporated into rod-cells have supported this notion. The extent of the contribution of calcium, however, remains unresolved. We now show that light-dependent changes in sensitivity in amphibian photoreceptors can be abolished by preventing movements of Ca2+ across the outer-segment plasma membrane. These experiments demonstrate that light adaptation in photoreceptors is mediated in cones primarily, and in rods perhaps exclusively, by changes in Cai2+.
ISSN:0028-0836
1476-4687
DOI:10.1038/334067a0