Document Detail

Experimental protocols alter phototransduction: the implications for retinal processing at visual threshold.
MedLine Citation:
PMID:  21389222     Owner:  NLM     Status:  MEDLINE    
Vision in dim light, when photons are scarce, requires reliable signaling of the arrival of single photons. Rod photoreceptors accomplish this task through the use of a G-protein-coupled transduction cascade that amplifies the activity of single active rhodopsin molecules. This process is one of the best understood signaling cascades in biology, yet quantitative measurements of the amplitude and kinetics of the rod's response in mice vary by a factor of ∼ 2 across studies. What accounts for these discrepancies? We used several experimental approaches to reconcile differences in published properties of rod responses. First, we used suction electrode recordings from single rods to compare measurements across a range of recording conditions. Second, we compared measurements of single-cell photocurrents to estimates of rod function from in vitro electroretinograms. Third, we assayed the health of the post-receptor retinal tissue in these different conditions. Several salient points emerge from these experiments: (1) recorded responses can be altered dramatically by how the retina is stored; (2) the kinetics of the recovery of responses to bright but not dim flashes are strongly sensitive to the extracellular concentration of magnesium; (3) experimental conditions that produce very different single-photon responses measured in single rods produce near identical derived rod responses from the electroretinogram. The dependence of rod responses on experimental conditions will be a key consideration in efforts to extract general principles of G-protein signaling from studies of phototransduction and to relate these signals to downstream mechanisms that facilitate visual sensitivity.
Anthony W Azevedo; Fred Rieke
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of neuroscience : the official journal of the Society for Neuroscience     Volume:  31     ISSN:  1529-2401     ISO Abbreviation:  J. Neurosci.     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-03-10     Completed Date:  2011-05-11     Revised Date:  2014-09-15    
Medline Journal Info:
Nlm Unique ID:  8102140     Medline TA:  J Neurosci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3670-82     Citation Subset:  IM    
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MeSH Terms
Magnesium / metabolism
Photic Stimulation
Retina / physiology*
Retinal Rod Photoreceptor Cells / physiology*
Signal Transduction / physiology*
Vision, Ocular / physiology*
Grant Support
NS053521/NS/NINDS NIH HHS; P30 EY001730/EY/NEI NIH HHS; R01 EY011850/EY/NEI NIH HHS; R01 EY011850-15/EY/NEI NIH HHS; //Howard Hughes Medical Institute; //Howard Hughes Medical Institute
Reg. No./Substance:

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