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Neuron. 1996 Aug;17(2):323-31.

Ca2+ dependence of dark- and light-adapted flash responses in rod photoreceptors.

Author information

1
Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle 98195, USA.

Abstract

Light adaptation is thought to be orchestrated by a Ca2+ feedback signal that desensitizes the response by speeding recovery. To evaluate the role of Ca2+ in adaptation, we compared the effect of lowered Ca2+ on response properties in darkness and during adaptation. Internal Ca2+ was reduced from its normal resting dark level (535 nM) by either background illumination or exposure to Ringer's solution containing low Ca2+ and/or cyclic GMP-gated channel blockers in darkness. Ca2+ reductions in light decreased the activation gain of the transduction process and speeded recovery kinetics, while equivalent Ca2+ reductions in darkness caused similar gain reduction without accelerating recovery. This indicates that adaptational changes in the response are not due purely to feedback effects on recovery.

PMID:
8780655
DOI:
10.1016/s0896-6273(00)80163-4
[Indexed for MEDLINE]
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