Document Detail

Fatigue and posttetanic potentiation in single muscle fibers of the frog.
MedLine Citation:
PMID:  300990     Owner:  NLM     Status:  MEDLINE    
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.
J L Vergara; S I Rapoprot; V Nassar-Gentina
Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  The American journal of physiology     Volume:  232     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1977 May 
Date Detail:
Created Date:  1977-06-30     Completed Date:  1977-06-30     Revised Date:  2009-10-27    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  C185-90     Citation Subset:  IM    
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MeSH Terms
Calcium / metabolism
Electric Stimulation
Hypertonic Solutions
Muscle Contraction*
Muscles / metabolism*
Rana pipiens
Time Factors
Reg. No./Substance:
0/Hypertonic Solutions; 7440-70-2/Calcium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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