Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1992-10-13
pubmed:abstractText
1. We have undertaken a theoretical analysis of the steps contributing to the phototransduction cascade in vertebrate photoreceptors. We have explicitly considered only the activation steps, i.e. we have not dealt with the inactivation reactions. 2. From the theoretical analysis we conclude that a single photoisomerization leads to activation of the phosphodiesterase (PDE) with a time course which approximates a delayed ramp; the delay is contributed by several short first-order delay stages. 3. We derive a method for extracting the time course of PDE activation from the measured electrical response, and we apply this method to recordings of the photoresponse from salamander rods. The results confirm the prediction that the time course of PDE activation is a delayed ramp, with slope proportional to light intensity; the initial delay is about 10-20 ms. 4. We derive approximate analytical solutions for the electrical response of the photoreceptor to light, both for bright flashes (isotropic conditions) and for single photons (involving longitudinal diffusion of cyclic GMP in the outer segment). The response to a brief flash is predicted to follow a delayed Gaussian function of time, i.e. after an initial short delay the response should begin rising in proportion to t2. Further, the response-intensity relation is predicted to obey an exponential saturation. 5. These predictions are compared with experiment, and it is shown that the rising phase of the flash response is accurately described over a very wide range of intensities. We conclude that the model provides a comprehensive description of the activation steps of phototransduction at a molecular level.
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-112243, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-1690932, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-1901231, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-1962979, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-1964967, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2128335, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2154965, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2158346, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2168406, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2194224, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2211004, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-224596, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2423011, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2436571, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2441524, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2448798, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2455233, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2467600, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2473194, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2473195, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2573396, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2578616, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2621632, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2832596, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2833739, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-2988577, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-3018756, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-3032081, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-307603, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-4449052, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-5044581, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-6092516, http://linkedlifedata.com/resource/pubmed/commentcorrection/1326052-6798202
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0022-3751
pubmed:author
pubmed:issnType
Print
pubmed:volume
449
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
719-58
pubmed:dateRevised
2010-9-7
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
A quantitative account of the activation steps involved in phototransduction in amphibian photoreceptors.
pubmed:affiliation
Physiological Laboratory, University of Cambridge.
pubmed:publicationType
Journal Article