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Energy balance studies in frog skeletal muscles shortening at one-half maximal velocity.
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MedLine Citation:
PMID:  6332877     Owner:  NLM     Status:  MEDLINE    
High-energy phosphate metabolism and energy liberated as heat and work were measured in 3-s tetani of frog sartorius muscle at 0 degree C. Two contraction periods were studied: (a) a 0.35-s period of shortening near half-maximum velocity beginning after 2 s of isometric stimulation, and (b) a 0.65-s isometric period immediately following the shortening. There were no significant changes in levels of ATP, ADP, or AMP in the two contraction periods. The observed changes in inorganic phosphate and creatine levels indicated that the only significant reaction occurring was phosphocreatine splitting. The mean rate of high-energy phosphate splitting during the shortening, 1.60 +/- 0.23 mumol X g-1 X s-1 (n = 24), was about fivefold higher than that in the 1-s period in the isometric tetanus, 0.32 +/- 0.11 mumol X g-1 X s-1 (n = 17), observed in our previous study. The mean rate in the post-shortening period, 0.46 +/- 0.13 mumol X g-1 X s-1 (n = 17), was not significantly different from that in the 1-s period in the isometric tetanus. A large amount of heat plus work was produced during the shortening period, and this could be accounted for by simultaneous chemical changes. In the post-shortening period, the observed enthalpy was also accounted for by simultaneous chemical reactions. Thus, the present result is in sharp contrast to that obtained from a similar study performed at a shortening at Vmax, where an enthalpy excess was produced during shortening and an enthalpy deficit was produced during the period following the shortening.
E Homsher; T Yamada; A Wallner; J Tsai
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of general physiology     Volume:  84     ISSN:  0022-1295     ISO Abbreviation:  J. Gen. Physiol.     Publication Date:  1984 Sep 
Date Detail:
Created Date:  1984-11-20     Completed Date:  1984-11-20     Revised Date:  2008-11-20    
Medline Journal Info:
Nlm Unique ID:  2985110R     Medline TA:  J Gen Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  347-59     Citation Subset:  IM    
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MeSH Terms
Energy Metabolism*
Muscle Contraction*
Muscles / metabolism
Phosphates / metabolism
Rana pipiens
Time Factors
Grant Support
Reg. No./Substance:

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

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Journal Information
Journal ID (nlm-ta): J Gen Physiol
ISSN: 0022-1295
ISSN: 1540-7748
Publisher: The Rockefeller University Press
Article Information
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Print publication date: Day: 1 Month: 9 Year: 1984
Volume: 84 Issue: 3
First Page: 347 Last Page: 359
ID: 2228746
Publisher Id: 85008669
PubMed Id: 6332877

Energy balance studies in frog skeletal muscles shortening at one-half maximal velocity

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