Document Detail

Acidosis inhibits oxidative phosphorylation in contracting human skeletal muscle in vivo.
MedLine Citation:
PMID:  14514869     Owner:  NLM     Status:  MEDLINE    
This study tested the hypothesis that acidic pH inhibits oxidative ATP supply during exercise in hand (first dorsal interosseus, FDI) and lower limb (leg anterior compartment, LEG) muscles. We measured oxidative flux and estimated mitochondrial capacity using the changes in creatine phosphate concentration ([PCr]) and pH as detected by 31P magnetic resonance (MR) spectroscopy during isometric exercise and recovery. The highest oxidative ATP flux in sustained exercise was about half the estimated mitochondrial capacity in the LEG (0.38 +/- 0.06 vs. 0.90 +/- 0.14 mM ATP s(-1), respectively), but at the estimated capacity in the FDI (0.61 +/- 0.05 vs. 0.61 +/- 0.09 mM ATP s(-1), respectively). During sustained exercise at a higher contraction rate, intracellular acidosis (pH < 6.88) prevented a rise in oxidative flux in the LEG and FDI despite significantly increased [ADP]. We tested whether oxidative flux could increase above that achieved in sustained exercise by raising [ADP] (> 0.24 mM) and avoiding acidosis using burst exercise. This exercise raised oxidative flux (0.69 +/- 0.05 mM ATP s(-1)) to nearly twice that found with sustained exercise in the LEG and matched (0.65 +/- 0.11 mM ATP s(-1)) the near maximal flux seen during sustained exercise in the FDI. Thus both muscles reached their highest oxidative fluxes in the absence of acidosis. These results show that acidosis inhibits oxidative phosphorylation in vivo and can limit ATP supply in exercising muscle to below the mitochondrial capacity.
Sharon A Jubrias; Gregory J Crowther; Eric G Shankland; Rodney K Gronka; Kevin E Conley
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.     Date:  2003-09-26
Journal Detail:
Title:  The Journal of physiology     Volume:  553     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2003 Dec 
Date Detail:
Created Date:  2003-12-03     Completed Date:  2004-09-23     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  589-99     Citation Subset:  IM    
Department of Radiology, University of Washington Medical Center, Seattle, WA 98195, USA.
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MeSH Terms
Acidosis / metabolism,  physiopathology*
Adenosine Diphosphate / metabolism
Adenosine Triphosphate / metabolism
Exercise / physiology
Exercise Test
Hand / physiology
Hydrogen-Ion Concentration
Leg / physiology
Magnetic Resonance Spectroscopy
Middle Aged
Muscle Contraction / physiology*
Muscle, Skeletal / metabolism*
Oxidative Phosphorylation*
Phosphocreatine / metabolism
Rest / physiology
Grant Support
Reg. No./Substance:
56-65-5/Adenosine Triphosphate; 58-64-0/Adenosine Diphosphate; 67-07-2/Phosphocreatine

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