Linked Life Data

1698916

Source:http://linkedlifedata.com/resource/pubmed/id/1698916

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1990-11-15
pubmed:abstractText
Experiments were performed on rod photoreceptors isolated from the eye of the larval tiger salamander to determine if the same or different mechanisms underlie the desensitization produced by dim background light (background adaptation) and that which persists in the steady state in darkness after a significant fraction of the photopigment is bleached (bleaching adaptation). We have examined adaptational effects after light that bleached between approximately 50% and 95% of the photopigment under conditions which preclude pigment regeneration. The steady-state desensitization, far greater than that predicted by quantum-catch loss, is relieved upon regeneration of the visual pigment with 11-cis retinal. We measured the spread of desensitization along the long axis of the rod after a local bright bleach at one end by comparing responses to dim local test flashes elicited in different regions of the outer segment, before and after bleaching. The space constant for this spread was less than 2.5 microns. We have previously measured the space constant for the longitudinal spread of desensitization during a local dim background in Ambystoma rods to be 7 microns. This is similar to a space constant of 6 microns measured under similar conditions in Bufo rods by Lamb et al. (1981. J. Physiol. 319:463-496). If calcium carries the signal for background desensitization, this difference in space constant for background and bleaching adaptation precludes it as the messenger for the steady component of bleaching adaptation. Experiments with isobutylmethyl xanthine (IBMX) also indicate that Ca2+ as well as c-GMP are unlikely regulators of bleaching desensitization, since elevation of cytosolic levels of both of these internal messengers by IBMX has little effect on sensitivity in bleach-adapted cells. All of our findings are consistent with the notion that bleaching adaptation is not mediated by a freely diffusible cytoplasmic messenger.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0022-1295
pubmed:author
pubmed:issnType
Print
pubmed:volume
96
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
345-72
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Cellular mechanisms that underlie bleaching and background adaptation.
pubmed:affiliation
Department of Physiology, Boston University School of Medicine, Massachusetts 02118.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.