Document Detail

Effect of functional overload on enzyme levels in different types of skeletal muscle.
MedLine Citation:
PMID:  138668     Owner:  NLM     Status:  MEDLINE    
The effects of bilateral functional overload on enzyme changes in fast-twitch plantaris muscles were studied on different groups of rats: 1) normal-control; 2) normal-exercise; 3) overload-control; and 4) overload-exercise. Overload was accomplished by surgical elimination of synergists. Exercising groups walked up a 65% grade, 3 m/min, 2 h/day. Peak muscle enlargement of the overload groups was reached after 5 wk. Citrate synthase, phosphofructokinase, and myofibril ATPase activities were consistantly depressed by approximately 30%, 40%, and 18%, respectively, in overload as compared to normal groups. Daily exercise prevented the decrease in only citrate synthase activity. Unilateral overload of medial gastrocnemius muscle indicated that both fast-twitch oxidative-glycogenolytic and fast-twitch glycogenolytic fiber types undergo enzyme changes in response to the functional stress. However, changes in the former were in closer agreement with the net changes seen in the plantaris than the latter. Soleus muscle responded to overload primarily with marked reductions in respiratory capacity. These findings suggest that certain enzyme systems are altered with functional overload in different fiber types. However, the alterations in certain enzyme systems may, in part, be independent of the process of hypertrophy.
K M Baldwin; W G Cheadle; O M Martinez; D A Cooke
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of applied physiology: respiratory, environmental and exercise physiology     Volume:  42     ISSN:  0161-7567     ISO Abbreviation:  J Appl Physiol Respir Environ Exerc Physiol     Publication Date:  1977 Feb 
Date Detail:
Created Date:  1977-04-28     Completed Date:  1977-04-28     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  7801242     Medline TA:  J Appl Physiol Respir Environ Exerc Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  312-7     Citation Subset:  IM; S    
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MeSH Terms
Adenosine Triphosphatases / metabolism
Citrate (si)-Synthase / metabolism
Hypertrophy / etiology
Muscles / enzymology*,  pathology
Phosphofructokinase-1 / metabolism
Physical Conditioning, Animal*
Stress, Physiological / complications,  enzymology
Reg. No./Substance:
EC (si)-Synthase; EC; EC 3.6.1.-/Adenosine Triphosphatases

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

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