Document Detail

Effects of muscle glycogen and plasma FFA availability on human metabolic responses in cold water.
MedLine Citation:
PMID:  1757356     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to investigate whether simultaneous alterations in the availability of plasma free fatty acids and muscle glycogen would impair the maintenance of thermal balance during cold water immersion in humans. Eight seminude subjects were immersed on two occasions in 18 degrees C water for 90 min or until rectal temperature (Tre) decreased to 35.5 degrees C. Each immersion followed 2.5 days of a specific dietary and exercise regimen designed to elicit low (LOW) or high glycogen levels (HIGH) in large skeletal muscle groups. Nicotinic acid (1.6 mg/kg) was administered for 2 h before and during immersion to inhibit white adipose tissue lipolysis. Biopsies from the vastus lateralis showed that the glycogen concentration before the immersion was significantly lower in LOW than in HIGH (223 +/- 19 vs. 473 +/- 24 mmol glucose units/kg dry muscle). However, the mean rates of glycogen utilization were not significantly different between trials (LOW 0.62 +/- 0.14 vs. HIGH 0.88 +/- 0.15 mmol glucose Nicotinic acid dramatically reduced plasma free fatty acid levels in both trials, averaging 127 +/- 21 mumol/l immediately before the immersion. Cold water immersion did not significantly alter those levels. Plasma glucose levels were significantly reduced after cold water immersion to a similar extent in both trials (18 +/- 4%). Mean respiratory exchange ratio at rest and during immersion was greater in HIGH than LOW, whereas there were no intertrial differences in O2 uptake. The calculated average metabolic heat production during immersion tended to be lower (P = 0.054) in LOW than in HIGH (15.3 +/- 1.9 vs. 17.5 +/- 1.9 kJ/min).(ABSTRACT TRUNCATED AT 250 WORDS)
L Martineau; I Jacobs
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  71     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1991 Oct 
Date Detail:
Created Date:  1992-02-05     Completed Date:  1992-02-05     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1331-9     Citation Subset:  IM    
Defence and Civil Institute of Environmental Medicine, North York, Ontario, Canada.
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MeSH Terms
Blood Glucose / metabolism
Body Temperature / drug effects,  physiology
Body Temperature Regulation / physiology
Cold Temperature*
Epinephrine / blood
Exercise / physiology
Fatty Acids, Nonesterified / blood*
Glycerol / blood
Glycogen / physiology*
Lipolysis / drug effects
Metabolism / physiology*
Muscles / physiology*
Niacin / pharmacology
Norepinephrine / blood
Reg. No./Substance:
0/Blood Glucose; 0/Fatty Acids, Nonesterified; 51-41-2/Norepinephrine; 51-43-4/Epinephrine; 56-81-5/Glycerol; 59-67-6/Niacin; 9005-79-2/Glycogen

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

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