Linked Life Data

10632586

Source:http://linkedlifedata.com/resource/pubmed/id/10632586

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2000-2-9
pubmed:abstractText
The capacitance technique was used to investigate exocytosis at the ribbon synapse of depolarizing bipolar cells from the goldfish retina. When the Ca(2+) current was activated strongly, the rapidly releasable pool of vesicles (RRP) was released with a single rate-constant of approximately 300-500 sec(-1). However, when the Ca(2+) current was activated weakly by depolarization in the physiological range (-45 to -25 mV), exocytosis from the RRP occurred in two phases. After the release of 20% or more of the RRP, the rate-constant of exocytosis fell by a factor of 4-10. Thus, synaptic depression was caused by a reduced sensitivity to Ca(2+) influx, as well as simple depletion of the RRP. In the resting state, the rate of exocytosis varied with the amplitude of the Ca(2+) current raised to the power of 2. In the depressed state, the sensitivity to Ca(2+) influx was reduced approximately fourfold. The initial phase of exocytosis accelerated e-fold for every 2.1 mV depolarization over the physiological range and averaged 120 sec(-1) at -25 mV. The synapse of depolarizing bipolar cells therefore responds to a step depolarization in a manner similar to a high-pass filter. This transformation appears to be determined by the presence of rapidly releasable vesicles with differing sensitivities to Ca(2+) influx. This might occur if vesicles were docked to the plasma membrane at different distances from Ca(2+) channels. These results suggest that the ribbon synapse of depolarizing bipolar cells may be a site of adaptation in the retina.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
1529-2401
pubmed:author
pubmed:issnType
Electronic
pubmed:day
15
pubmed:volume
20
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
568-78
pubmed:dateRevised
2003-11-14
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Synaptic depression and the kinetics of exocytosis in retinal bipolar cells.
pubmed:affiliation
Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 2QH, United Kingdom.
pubmed:publicationType
Journal Article