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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
5
|
pubmed:dateCreated |
1977-6-30
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pubmed:abstractText |
At 15 degrees C, direct stimulation of frog single muscle fibers at a frequency of 20 Hz produced a tetanic tension that remained constant for 20 s and then declined. The decline was reversed during 1-s interruptions of the stimulus train in the first 50 s of stimulation, but not with longer stimulation. Posttetanic potentiation (PTP), characterized by prolonged twitch relaxation and contraction times and elevation of twitch height, remained for 10-40 min after a 10-s tetanus and for at least 90 min after a 50- to 150-s tetanus. Posttetanic fatigue appeared only after at least 50s of tetanic stimulation. Fatigue was manifested invariably by a reduction in the height of a 200-ms tetanic contraction and usually by a reduction in twitch height after PTP. Fatigued fibers recovered normal contractile responses in 40-160 min. Hypertonic solutions, which blocked contraction in response to tetanic stimulation, prevented posttetanic fatigue but not PTP. The observations suggest that fatigue is caused by a failure in excitation-contraction coupling, probably in relation to consumption of metabolic substrates. Even 10-s tetani which do not produce fatigue can affect muscle contractile function for up to 40 min.
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pubmed:language |
eng
|
pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
|
pubmed:month |
May
|
pubmed:issn |
0002-9513
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pubmed:author | |
pubmed:issnType |
Print
|
pubmed:volume |
232
|
pubmed:owner |
NLM
|
pubmed:authorsComplete |
Y
|
pubmed:pagination |
C185-90
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pubmed:dateRevised |
2009-10-27
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pubmed:meshHeading |
pubmed-meshheading:300990-Animals,
pubmed-meshheading:300990-Anura,
pubmed-meshheading:300990-Calcium,
pubmed-meshheading:300990-Electric Stimulation,
pubmed-meshheading:300990-Hypertonic Solutions,
pubmed-meshheading:300990-Muscle Contraction,
pubmed-meshheading:300990-Muscles,
pubmed-meshheading:300990-Rana pipiens,
pubmed-meshheading:300990-Time Factors
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pubmed:year |
1977
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pubmed:articleTitle |
Fatigue and posttetanic potentiation in single muscle fibers of the frog.
|
pubmed:publicationType |
Journal Article,
In Vitro
|