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rdf:type | |
lifeskim:mentions | |
pubmed:dateCreated |
1997-2-21
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pubmed:abstractText |
1. The influence of divalent cations was investigated on the noradrenaline-activated non-selective cation current (Icat) in freshly dispersed smooth muscle cells of rabbit portal vein. 2. Reduction of external calcium concentration ([Ca2+]o) from 1.5 mM to 'test' levels of 100-500 microM during stimulation of Icat produced a sustained potentiation of Icat, which indicates an inhibitory action of Cao2+. With 'test' concentrations lower than 100 microM Cao2+ the amplitude of Icat was initially potentiated and then the current subsequently declined. Under these conditions re-addition of 1.5 mM Cao2+ transiently activated Icat which demonstrates an additional facilitatory action of [Ca2+]o. The half-maximal [Ca2+]o for the facilitatory and inhibitory action on Icat was 6 and 400 microM, respectively. 3. When [Ca2+]o was decreased to very low levels (< 10 nM) by inclusion of 1 mM BAPTA in nominally Ca(2+)-free external solution, Icat could still be evoked by noradrenaline. This suggested that Ca2+ is not obligatory for activation of Icat but merely modulatory. 4. In 1.5 mM Cao2+ the current-voltage (I-V) relationship of Icat was S-shaped with a reversal potential (Er) of about +9 mV. The I-V characteristics and Er of the potentiated current in 200 microM Cao2+ were not markedly different from those in 1.5 mM Cao2+. 5. During the noradrenaline-induced Icat, removal of external Mg2+ caused a small increase in the amplitude of Icat which was not as great as that seen on reduction of [Ca2+]o and there was no facilitatory effect of Mgo2+. 6. These results indicate that external Ca2+ has a dual action on Icat, both facilitating and inhibiting the current. This dual action is not shared with external Mg2+.
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pubmed:grant | |
pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730584-1696988,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730584-1724672,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730584-1770436,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730584-2118179,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730584-2170596,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730584-2473199,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730584-7505656,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8730584-7693920
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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/1,2-bis(2-aminophenoxy)ethane-N,N,N'...,
http://linkedlifedata.com/resource/pubmed/chemical/Anions,
http://linkedlifedata.com/resource/pubmed/chemical/Calcium,
http://linkedlifedata.com/resource/pubmed/chemical/Cations, Monovalent,
http://linkedlifedata.com/resource/pubmed/chemical/Egtazic Acid,
http://linkedlifedata.com/resource/pubmed/chemical/Ion Channels,
http://linkedlifedata.com/resource/pubmed/chemical/Magnesium,
http://linkedlifedata.com/resource/pubmed/chemical/Norepinephrine
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pubmed:status |
MEDLINE
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pubmed:month |
Apr
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pubmed:issn |
0022-3751
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
1
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pubmed:volume |
492 ( Pt 1)
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
75-88
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pubmed:dateRevised |
2010-8-25
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pubmed:meshHeading |
pubmed-meshheading:8730584-Animals,
pubmed-meshheading:8730584-Anions,
pubmed-meshheading:8730584-Calcium,
pubmed-meshheading:8730584-Cations, Monovalent,
pubmed-meshheading:8730584-Egtazic Acid,
pubmed-meshheading:8730584-Ion Channels,
pubmed-meshheading:8730584-Magnesium,
pubmed-meshheading:8730584-Membrane Potentials,
pubmed-meshheading:8730584-Muscle, Smooth, Vascular,
pubmed-meshheading:8730584-Norepinephrine,
pubmed-meshheading:8730584-Patch-Clamp Techniques,
pubmed-meshheading:8730584-Portal Vein,
pubmed-meshheading:8730584-Rabbits
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pubmed:year |
1996
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pubmed:articleTitle |
Dual effect of external Ca2+ on noradrenaline-activated cation current in rabbit portal vein smooth muscle cells.
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pubmed:affiliation |
Department of Pharmacology, St George's Hospital Medical School, London, UK.
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pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, Non-U.S. Gov't
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