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rdf:type |
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lifeskim:mentions |
umls-concept:C0006675,
umls-concept:C0007634,
umls-concept:C0018787,
umls-concept:C0030685,
umls-concept:C0036226,
umls-concept:C0205171,
umls-concept:C0205263,
umls-concept:C0391871,
umls-concept:C0680255,
umls-concept:C1140999,
umls-concept:C1283071,
umls-concept:C1963578
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pubmed:issue |
3
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pubmed:dateCreated |
1976-1-2
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pubmed:abstractText |
1. Fragments of single cardiac cells were obtained by homogenization of ventricular tissue from adult rats. Remaining pieces of sacrolemma were removed by micro-dissection. Tension was recorded from the ends of the skinned (sarcolemma-free) cells with a photodiode force transducer. 2. In the presence of a strong buffering of the free [Ca2+] with 4-0 mM total EGTA, a tonic tension was obtained that increased according to t sigmoid curve when the free ([Ca2+] was increased from 10(-6-75)M to 10(-5-0)M. This curve was not modified by the destruction of the sarcoplasmic reticulum (SR) by the detergent Brij 58. Therefore, the tonic tension corresponded to the direct effect of the free [Ca2+] present in the buffer on the myofilaments. 3. In the presence of a slight buffering of the free [Ca2+] with 0-050 mM total EGTA, cyclic contractions were observed that were attributed to cyclic releases and re-sequestrations of Ca2+ by the SR. The absence of effect of azide and ruthenium red on the cyclic contractions obtained at a free [Ca2+] lower than 10(-6-50)M demonstrated that the mitochondria played no role in the triggering of these contractions. 4. Cyclic contractions were induced by a slight variation of free [Ca2+] in the buffer from 10(-7-65)M to 10(-7-40)M. Their amplitude at 10(-7-40)M free Ca2+ was equal to the tonic tension developed by a free [Ca2+] 20 times higher applied to the myofilaments when the SR was destroyed by detergent or functionally inhibited by high total [EGTA]. It was concluded that these cyclic contractions corresponded to a Ca2+-triggered release of Ca2+ from the SR. 5. The cyclic contractions were induced by the filling of the SR with Ca2+ to a critical level at which it released a fraction of the Ca2+ it contained. Each contraction was followed by a re-sequestration of Ca2+, the kinetics of which conditioned the duration of the cycles. 6. The amplitude of the cyclic contractions increased when the free [Ca2+] that triggered them was increased. This gradation was deemed incompatible with a simple regenerative process, which should produce an all-or-nothing response. Additional process, such as a modulation of the Ca2+ release by free [Mg2+] and [ADP] may help to explain the gradation of the contractions. 7. It was concluded that a Ca2+-triggered release of Ca2+ from the SR of rat ventricular cells may amplify the Ca2+ flux crossing the sarcolemma during the plateau of the action potential, thereby permitting the activation of the myofilaments.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-1177102,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-14114498,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-14179458,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-14478319,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-16991336,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4148698,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4196573,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4217348,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4252537,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4264736,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4341466,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4537984,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4540418,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4543066,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4544880,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4548716,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4591638,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4805702,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4812634,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4822790,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-4826929,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5011002,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5046147,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5046150,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5130607,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5335863,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5409477,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5456208,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5474799,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5539338,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5539339,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5549096,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5688082,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5715508,
http://linkedlifedata.com/resource/pubmed/commentcorrection/809571-5765859
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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 |
Aug
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pubmed:issn |
0022-3751
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
249
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
469-95
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:809571-Animals,
pubmed-meshheading:809571-Azides,
pubmed-meshheading:809571-Caffeine,
pubmed-meshheading:809571-Calcium,
pubmed-meshheading:809571-Egtazic Acid,
pubmed-meshheading:809571-Heart Ventricles,
pubmed-meshheading:809571-Myocardial Contraction,
pubmed-meshheading:809571-Myocardium,
pubmed-meshheading:809571-Periodicity,
pubmed-meshheading:809571-Rats,
pubmed-meshheading:809571-Ruthenium Red,
pubmed-meshheading:809571-Sarcoplasmic Reticulum
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pubmed:year |
1975
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pubmed:articleTitle |
Contractions induced by a calcium-triggered release of calcium from the sarcoplasmic reticulum of single skinned cardiac cells.
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pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, U.S. Gov't, P.H.S.
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