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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
10
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pubmed:dateCreated |
1994-11-14
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pubmed:abstractText |
We simultaneously measured presynaptic free calcium ion concentration ([Ca2+]i) and synaptic strength at the crayfish claw opener neuromuscular junction (nmj) under a variety of experimental conditions. Our experiments were designed both to test the hypothesis that elevated [Ca2+]i is necessary and sufficient for the induction of a form of synaptic enhancement that persists for several seconds after tetanic stimulation--augmentation--and to determine the quantitative relationship between elevated [Ca2+]i and this enhancement. Action potential trains increased [Ca2+]i and enhanced transmission. During the decay phase of synaptic enhancement known as augmentation (time constant of decay approximately 7 sec at 20 degrees C with < 200 microM fura-2 in terminals), [Ca2+]i was elevated 700 nM or less above rest and an essentially linear relationship between [Ca2+]i and enhancement was observed. Introduction of exogenous Ca2+ buffers into the presynaptic terminal slowed the buildup and recovery kinetics of both [Ca2+]i and the component of synaptic enhancement corresponding to augmentation. The slope of the relationship relating delta [Ca2+]i to augmentation was not changed. The time course of augmentation and recovery of [Ca2+]i remained correlated as the temperature of the preparation was changed from about 10 degrees C to 20 degrees C, but the quantitative relationship of enhancement to [Ca2+]i was increased more than two- to threefold. During moderate frequency trains of action potentials, a slowly developing component of the total synaptic enhancement was approximately linearly related to residual [Ca2+]i measured with fura-2. The quantitative relationship between [Ca2+]i and this component of synaptic enhancement during trains was the same as that during synaptic augmentation after trains.(ABSTRACT TRUNCATED AT 250 WORDS)
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Calcium,
http://linkedlifedata.com/resource/pubmed/chemical/Fura-2,
http://linkedlifedata.com/resource/pubmed/chemical/Monensin,
http://linkedlifedata.com/resource/pubmed/chemical/Ouabain,
http://linkedlifedata.com/resource/pubmed/chemical/Sodium-Potassium-Exchanging ATPase
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pubmed:status |
MEDLINE
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pubmed:month |
Oct
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pubmed:issn |
0270-6474
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
14
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
5885-902
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pubmed:dateRevised |
2007-11-15
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pubmed:meshHeading |
pubmed-meshheading:7931551-Action Potentials,
pubmed-meshheading:7931551-Animals,
pubmed-meshheading:7931551-Astacoidea,
pubmed-meshheading:7931551-Calcium,
pubmed-meshheading:7931551-Fluorometry,
pubmed-meshheading:7931551-Fura-2,
pubmed-meshheading:7931551-Image Enhancement,
pubmed-meshheading:7931551-Microscopy, Fluorescence,
pubmed-meshheading:7931551-Monensin,
pubmed-meshheading:7931551-Muscle, Skeletal,
pubmed-meshheading:7931551-Neuromuscular Junction,
pubmed-meshheading:7931551-Ouabain,
pubmed-meshheading:7931551-Presynaptic Terminals,
pubmed-meshheading:7931551-Reference Values,
pubmed-meshheading:7931551-Regression Analysis,
pubmed-meshheading:7931551-Sodium-Potassium-Exchanging ATPase,
pubmed-meshheading:7931551-Temperature
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pubmed:year |
1994
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pubmed:articleTitle |
A quantitative measurement of the dependence of short-term synaptic enhancement on presynaptic residual calcium.
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pubmed:affiliation |
Biological Computation Research Department, AT&T Bell Laboratories, Murray Hill, New Jersey 07974.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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