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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
3
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pubmed:dateCreated |
1996-1-4
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pubmed:abstractText |
Block of the muscarinic K+ current (iK,ACh) by Ba2+ has been studied in guinea-pig atrial cells using the whole-cell patch-clamp technique. The dose-response curve for the block of iK,ACh can be fitted assuming that a muscarinic K+ channel is blocked when a single Ba2+ ion binds to it (apparent dissociation constant, Kd = 125 microM at 0 mV). Block was voltage and time dependent. The voltage dependence can be explained by Ba2+ binding to a site within the pore of the channel, 36% across the width of the membrane electric field (from the outside). Raising the bathing K+ concentration reduced Ba2+ block of iK,ACh, which suggests that Ba2+ and K+ compete for a common binding site. When Ba2+ was added during an exposure to ACh (muscarinic K+ channel open), block of iK,ACh developed rapidly, but when Ba2+ was added prior to an exposure to ACh (muscarinic K+ channel closed), little block of iK,ACh was evident when ACh was first applied. This suggests that when the muscarinic K+ channel is closed in the absence of ACh, Ba2+ does not have access to the binding site within the pore of the channel. In conclusion, Ba2+ block of iK,ACh is concentration, voltage, time, K+ and state dependent.
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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/Barium,
http://linkedlifedata.com/resource/pubmed/chemical/Muscarinic Antagonists,
http://linkedlifedata.com/resource/pubmed/chemical/Potassium,
http://linkedlifedata.com/resource/pubmed/chemical/Potassium Channels,
http://linkedlifedata.com/resource/pubmed/chemical/Receptors, Muscarinic
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pubmed:status |
MEDLINE
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pubmed:month |
Jul
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pubmed:issn |
0031-6768
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
430
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
348-57
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:7491258-Animals,
pubmed-meshheading:7491258-Barium,
pubmed-meshheading:7491258-Binding Sites,
pubmed-meshheading:7491258-Electrophysiology,
pubmed-meshheading:7491258-Guinea Pigs,
pubmed-meshheading:7491258-Heart Atria,
pubmed-meshheading:7491258-Membrane Potentials,
pubmed-meshheading:7491258-Muscarinic Antagonists,
pubmed-meshheading:7491258-Myocardium,
pubmed-meshheading:7491258-Patch-Clamp Techniques,
pubmed-meshheading:7491258-Potassium,
pubmed-meshheading:7491258-Potassium Channels,
pubmed-meshheading:7491258-Receptors, Muscarinic
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pubmed:year |
1995
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pubmed:articleTitle |
Barium block of the muscarinic potassium current in guinea-pig atrial cells.
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pubmed:affiliation |
Department of Physiology, University of Leeds, UK.
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pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, Non-U.S. Gov't
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