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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
4
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pubmed:dateCreated |
1996-11-27
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pubmed:abstractText |
Single Ca2+ channel and whole cell currents were measured in smooth muscle cells dissociated from resistance-sized (100-microns diameter) rat cerebral arteries. We sought to quantify the magnitude of Ca2+ channel currents and activity under the putative physiological conditions of these cells: 2 mM [Ca2+]o, steady depolarizations to potentials between -50 and -20 mV, and (where possible) without extrinsic channel agonists. Single Ca2+ channel conductance was measured over a broad range of Ca2+ concentrations (0.5-80 mM). The saturating conductance ranged from 1.5 pS at 0.5 mM to 7.8 pS at 80 mM, with a value of 3.5 pS at 2 mM Ca (unitary currents of 0.18 pA at -40 mV). Both single channel and whole cell Ca2+ currents were measured during pulses and at steady holding potentials. Ca2+ channel open probability and the lower limit for the total number of channels per cell were estimated by dividing the whole-cell Ca2+ currents by the single channel current. We estimate that an average cell has at least 5,000 functional channels with open probabilities of 3.4 x 10(-4) and 2 x 10(-3) at -40 and -20 mV, respectively. An average of 1-10 (-40 mV and -20 mV, respectively) Ca2+ channels are thus open at physiological potentials, carrying approximately 0.5 pA steady Ca2+ current at -30 mV. We also observed a very slow reduction in open probability during steady test potentials when compared with peak pulse responses. This 4-10-fold reduction in activity could not be accounted for by the channel's normal inactivation at our recording potentials between -50 and -20 mV, implying that an additional slow inactivation process may be important in regulating Ca2+ channel activity during steady depolarization.
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pubmed:grant |
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-1312782,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-1332495,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-1338463,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-1373909,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-1375438,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-1380775,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-1381926,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-1698983,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-1721500,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-2163433,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-2165445,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-2417192,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-2428919,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-2454449,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-2475611,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-2481511,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-2541145,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-2557436,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-2560160,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-2848201,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-6207437,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-6270629,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-6296410,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-6744529,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-7381770,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-7971160,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/8722560-8271214
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Apr
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pubmed:issn |
0022-1295
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
107
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
459-72
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:8722560-3-Pyridinecarboxylic acid...,
pubmed-meshheading:8722560-Animals,
pubmed-meshheading:8722560-Calcium,
pubmed-meshheading:8722560-Calcium Channels,
pubmed-meshheading:8722560-Cerebral Arteries,
pubmed-meshheading:8722560-Dose-Response Relationship, Drug,
pubmed-meshheading:8722560-Female,
pubmed-meshheading:8722560-Muscle, Smooth,
pubmed-meshheading:8722560-Rats,
pubmed-meshheading:8722560-Rats, Sprague-Dawley
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pubmed:year |
1996
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pubmed:articleTitle |
Ca2+ currents in cerebral artery smooth muscle cells of rat at physiological Ca2+ concentrations.
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pubmed:affiliation |
Department of Pharmacology, University of Vermont, Burlington 05405, USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, U.S. Gov't, Non-P.H.S.,
Research Support, Non-U.S. Gov't
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