Document Detail


Effect of exercise on hexokinase distribution and mitochondrial respiration in skeletal muscle.
MedLine Citation:
PMID:  8072844     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Horses were subjected to treadmill running at 65% (submaximal) or 100% (maximal) VO2,max to examine the effects of exercise on subcellular distribution of hexokinase (HK) and on mitochondrial respiration. It is hypothesized that the fraction of HK bound to mitochondria will be reduced due to an elevation of glucose-6-phosphate (G-6-P) concentration in the exercising muscle and that such release of HK from mitochondria will depress oxidative phosphorylation. Changes in muscle G-6-P concentration, pH, subcellular HK distribution, mitochondrial respiration and other metabolites were determined in biopsy samples pre-exercise, immediately post-exercise and during the recovery phase. The fraction of HK associated with mitochondria decreased from 38% to 7% at the end of maximal exercise; exercise at VO2,max also reduced respiratory capacity of muscle homogenates by 20% and was associated with a fivefold increase in muscle [G-6-P], a potent agent known to dissociate HK from mitochondria. The HK distribution returned to normal within 60 min after exercise and the reassociation of the HK with mitochondria parallelled the removal of muscle G-6-P. No changes in muscle HK distribution and respiration were found following the submaximal exercise despite the fact that G-6-P was slightly elevated. Muscle concentrations of adenosine triphosphate, creatine phosphate and glycogen and pH dropped after exercise while lactate concentration increased. The amount of mitochondria-bound HK was also altered in vitro in a preparation of mitochondria isolated from rat skeletal muscle to examine the effect of the bound HK on mitochondrial respiration.(ABSTRACT TRUNCATED AT 250 WORDS)
Authors:
J Chen; P D Gollnick
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Pflügers Archiv : European journal of physiology     Volume:  427     ISSN:  0031-6768     ISO Abbreviation:  Pflugers Arch.     Publication Date:  1994 Jun 
Date Detail:
Created Date:  1994-09-26     Completed Date:  1994-09-26     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0154720     Medline TA:  Pflugers Arch     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  257-63     Citation Subset:  IM    
Affiliation:
Department of Veterinary and Comparative Anatomy, Pharmacology, College of Veterinary Medicine, Pullman, WA 99164-6520.
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MeSH Terms
Descriptor/Qualifier:
Adenosine Triphosphate / metabolism
Animals
Glucose-6-Phosphate
Glucosephosphates / metabolism
Glycogen / metabolism
Hexokinase / metabolism*
Horses
Hydrogen-Ion Concentration
Lactates / metabolism
Lactic Acid
Magnesium / physiology
Male
Mitochondria, Muscle / drug effects,  enzymology,  metabolism*
Oxygen Consumption
Phosphocreatine / metabolism
Physical Exertion / physiology*
Rats
Rats, Sprague-Dawley
Chemical
Reg. No./Substance:
0/Glucosephosphates; 0/Lactates; 50-21-5/Lactic Acid; 56-65-5/Adenosine Triphosphate; 56-73-5/Glucose-6-Phosphate; 67-07-2/Phosphocreatine; 7439-95-4/Magnesium; 9005-79-2/Glycogen; EC 2.7.1.1/Hexokinase

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


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