Abstract

The electrical signals of vertebrate photoreceptors are generated by modulation of an inward current of sodium ions at the outer segment. The mechanism by which Na enters the outer segment is not known, and there is little solid evidence about how light controls the conductance of the pores or carrier molecules that mediate the Na influx. We propose to examine the properties of the light-sensitive conductance and the mechaism of its control, using patch clamp and suction electrode recording, optical measurements, and injection of substances into isolated rods. We intend to approach the following questions: 1) What is the electrical conductance, temperature dependence and kinetic behaviour of the light-sensitive """"""""channel"""""""" in the surface membrane of the rod outer segment? 2) How does the channel respond to possible internal transmitters such as CA ions and cyclic GMP? 3) How does the internal concentration of free Ca change during a rod's response to light? 4) What is the origin of the continuous component of the electrical dark noise of rods? 5) What is the magnitude and power spectrum of the dark noise of cones, and how is the noise generated? 6) In the outer segment of a dark-adapted rod is there a longitudinal gradient of internal Na concentration? Is a Na gradient responsible for the different kinetics of transduction at the tip and base of the outer segment?

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY001543-14
Application #
3255999
Study Section
(SSS)
Project Start
1977-09-01
Project End
1990-08-31
Budget Start
1987-09-01
Budget End
1988-08-31
Support Year
14
Fiscal Year
1987
Total Cost
Indirect Cost

  Institution

Name
Stanford University
Department
Type
Schools of Medicine
DUNS #
800771545
City
Stanford
State
CA
Country
United States
Zip Code
94305

  Publications

Sampath, Alapakkam P; Baylor, Denis A (2002) Molecular mechanism of spontaneous pigment activation in retinal cones. Biophys J 83:184-93
Burns, M E; Baylor, D A (2001) Activation, deactivation, and adaptation in vertebrate photoreceptor cells. Annu Rev Neurosci 24:779-805
Middendorf, T R; Aldrich, R W; Baylor, D A (2000) Modification of cyclic nucleotide-gated ion channels by ultraviolet light. J Gen Physiol 116:227-52
Middendorf, T R; Aldrich, R W (2000) Effects of ultraviolet modification on the gating energetics of cyclic nucleotide-gated channels. J Gen Physiol 116:253-82
Rieke, F; Baylor, D A (2000) Origin and functional impact of dark noise in retinal cones. Neuron 26:181-6
Makino, C L; Groesbeek, M; Lugtenburg, J et al. (1999) Spectral tuning in salamander visual pigments studied with dihydroretinal chromophores. Biophys J 77:1024-35
Rieke, F; Baylor, D A (1998) Origin of reproducibility in the responses of retinal rods to single photons. Biophys J 75:1836-57
Erickson, M A; Lagnado, L; Zozulya, S et al. (1998) The effect of recombinant recoverin on the photoresponse of truncated rod photoreceptors. Proc Natl Acad Sci U S A 95:6474-9
Rieke, F; Baylor, D A (1996) Molecular origin of continuous dark noise in rod photoreceptors. Biophys J 71:2553-72
Baylor, D (1996) How photons start vision. Proc Natl Acad Sci U S A 93:560-5

Showing the most recent 10 out of 28 publications