Document Detail

Multiple controls of oxidative metabolism in living tissues as studied by phosphorus magnetic resonance.
MedLine Citation:
PMID:  3467315     Owner:  NLM     Status:  MEDLINE    
Three types of metabolic control of oxidative metabolism are observed in the various tissues that have been studied by phosphorous magnetic resonance spectroscopy. The principal control of oxidative metabolism in skeletal muscle is by ADP (or Pi/phosphocreatine). This conclusion is based upon studies of arm muscles of humans during steady-state exercise. A work-cost (Vm vs. Pi/phosphocreatine) relationship follows a Michaelis-Menten rectangular hyperbola, where Km values from 0.5 to 0.6 and Vmax values from 50 to 200 (at nearly constant pH) are found in linearized plots of the equation V/Vmax = 1/(1 + 0.6 phosphocreatine/Pi) where V is work level (which is equal to the velocity of the enzymatic reaction) and Vmax is the maximal work capacity that is a measure of the enzyme activity (E) of oxidative metabolism. Adaptation to exercise enhances the slope of the work-cost relationship and causes large changes in Vmax or E. A second metabolic control may enhance the slope of the work-cost relationship but not Vmax. For example, the initiation of exercise can lead to an improved characteristic that can be explained by 2-fold increased substrate delivery, for example, increased oxygen delivery by microcirculatory control. Cardiac tissue of the adult dog affords an example of optimal endurance performance adaptation and exhibits the steepest work-cost relationship observed and is attributed to a coordinated control of substrate delivery that may involve Ca2+ and inorganic phosphate control of NADH; control of O2 delivery may also be involved. The calculated work-cost relationship is similar to that observed in the beagle heart. The theoretical curve illustrates that the liability of multiple controls is a sharp break point in metabolic control at the end of the multiple control range--a possible cause of instability of cardiac performance at high V/Vmax.
B Chance; J S Leigh; J Kent; K McCully; S Nioka; B J Clark; J M Maris; T Graham
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  83     ISSN:  0027-8424     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  1986 Dec 
Date Detail:
Created Date:  1987-02-06     Completed Date:  1987-02-06     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  9458-62     Citation Subset:  IM; S    
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MeSH Terms
Acidosis / metabolism
Adenine Nucleotides / physiology*
Adenosine Diphosphate / metabolism
Energy Metabolism*
Magnetic Resonance Spectroscopy
Muscles / metabolism*
Myocardium / metabolism
NAD / metabolism
Oxygen / metabolism
Phosphocreatine / physiology*
Physical Endurance
Physical Exertion
Grant Support
Reg. No./Substance:
0/Adenine Nucleotides; 53-84-9/NAD; 58-64-0/Adenosine Diphosphate; 67-07-2/Phosphocreatine; 7782-44-7/Oxygen

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

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