Document Detail

Effect of extracellular osmolality on metabolism in contracting mammalian skeletal muscle in vitro.
MedLine Citation:
PMID:  20029514     Owner:  NLM     Status:  MEDLINE    
Extensive research has been conducted on hepatocyte metabolism perturbed under the influence of anisosmotic stress. However, much less is known about the behaviour of skeletal muscle metabolism under similar conditions. After establishing a working model to study anisosmotic stress in resting mammalian skeletal muscle, the current study tested the hypothesis that hyperosmotic (HYPER) stress would lead to increased creatine, lactate, and measured enzyme activity, whereas hypo-osmotic (HYPO) stress would lead to decreased metabolites and enzyme activity vs. iso-osmotic (ISO) stress post contraction. Rat soleus (SOL) and extensor digitorum longus (EDL) were isolated and incubated in an organ bath (95% O2, 5% CO2, pH 7.4, 25 degrees C) altered to targeted osmotic conditions (ISO, 290 osmol.L(-1); HYPO, 180 osmol.L(-1); HYPER, 400 osmol.L(-1)). Muscle samples were flash frozen after 10 min of contraction. Post contraction, muscle water content in the SOL HYPO condition was 18% greater than ISO, and HYPER had approximately 14% less water content than ISO (p < 0.05). In the HYPO condition, EDL had 21% greater water content than ISO, and HYPER had 17% less water content than ISO (p < 0.05). SOL HYPO resulted in higher phosphocreatine and lower lactate and creatine vs. HYPER (p < 0.05) but there were no differences in EDL between HYPO and HYPER. Pyruvate dehydrogenase activity increased in SOL HYPER vs. HYPO, whereas glycogen phosphorylase a increased in EDL HYPER vs. HYPO. In conclusion, fibre-type-specific responses exist after contraction such that when SOL muscle is perturbed in HYPER, as compared with HYPO, media, metabolic activity increases. Future work should focus on glucose uptake-regulation during anisosmotic conditions.
Naomi M Cermak; Paul J LeBlanc; Sandra J Peters; Rene Vandenboom; Brian D Roy
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Applied physiology, nutrition, and metabolism = Physiologie appliqu?e, nutrition et m?tabolisme     Volume:  34     ISSN:  1715-5312     ISO Abbreviation:  Appl Physiol Nutr Metab     Publication Date:  2009 Dec 
Date Detail:
Created Date:  2009-12-23     Completed Date:  2010-04-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101264333     Medline TA:  Appl Physiol Nutr Metab     Country:  Canada    
Other Details:
Languages:  eng     Pagination:  1055-64     Citation Subset:  IM    
Centre for Muscle Metabolism and Biophysics, Department of Physical Education and Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada.
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MeSH Terms
Creatine / analysis
Extracellular Fluid / chemistry*
Glycogen Phosphorylase, Muscle Form
Lactic Acid / analysis
Models, Biological
Muscle Contraction / physiology*
Muscle, Skeletal / chemistry,  enzymology,  metabolism*
Organ Specificity
Osmolar Concentration
Phosphocreatine / analysis
Pyruvate Dehydrogenase (Lipoamide) / metabolism
Random Allocation
Rats, Long-Evans
Stress, Physiological*
Time Factors
Water / analysis
Reg. No./Substance:
50-21-5/Lactic Acid; 57-00-1/Creatine; 67-07-2/Phosphocreatine; 7732-18-5/Water; EC Dehydrogenase (Lipoamide); EC 2.4.1.-/Glycogen Phosphorylase, Muscle Form

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

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