A cGMP-gated cation channel and phototransduction in depolarizing photoreceptors of the lizard parietal eye

Photoreceptors of the lizard parietal eye, unlike rods and cones but like most invertebrate photoreceptors, respond to light under dark-adapted conditions with a depolarization. Using excised-patch recordings, we have nonetheless found a cGMP-gated, non-selective cation channel present at high densi...

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Bibliographic Details
Published in:Vision research (Oxford) 1998-05, Vol.38 (10), p.1353-1357
Main Authors: Finn, John T, Xiong, Wei-Hong, Solessio, Eduardo C, Yau, King-Wai
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
cGMP
cGMP-gated channel
Cyclic GMP - metabolism
Dark Adaptation
Eye and associated structures. Visual pathways and centers. Vision
Fundamental and applied biological sciences. Psychology
In Vitro Techniques
Ion Channel Gating
Light
Lizards - physiology
Parietal eye
Patch-Clamp Techniques
Photoreceptor
Photoreceptor Cells - physiology
Phototransduction
Vertebrates: nervous system and sense organs
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Summary:Photoreceptors of the lizard parietal eye, unlike rods and cones but like most invertebrate photoreceptors, respond to light under dark-adapted conditions with a depolarization. Using excised-patch recordings, we have nonetheless found a cGMP-gated, non-selective cation channel present at high density at the presumptive light-sensitive part (the outer segment) of these cells. This channel resembles the rod cGMP-gated channel in its activation characteristics, and by showing a relative non-selectivity among alkali monovalent cations, a high permeability to Ca 2+, a high sensitivity to l- cis-diltiazem, as well as a negative modulation by Ca 2+–calmodulin. This channel appears to mediate phototransduction by opening in the light to produce the depolarizing response.
ISSN:0042-6989
1878-5646
DOI:10.1016/S0042-6989(97)00365-9