Document Detail

Accelerated glutamine synthesis in critically ill patients cannot maintain normal intramuscular free glutamine concentration.
MedLine Citation:
PMID:  10485436     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Muscle glutamine is severely depleted in critically ill patients (by approximately 50% to 80% of normal). Because muscle protein breakdown, and thus the release of glutamine from muscle protein, is enhanced in response to metabolic stress, the depletion of intramuscular glutamine could be due to its impaired synthesis or accelerated outward transport or both. METHODS: To distinguish these possibilities, we measured skeletal muscle glutamine metabolism in five critically ill patients by means of primed, continuous infusions of 5-15N-glutamine and ring-2H5-phenylalanine and compared them to values we previously reported for healthy volunteers. RESULTS: The intramuscular free glutamine concentration in patients was approximately 70% of that in healthy volunteers (5.8 +/- 0.6 mmol/L intracellular free water vs 21.5 +/- 2.8 mmol/L). Whole-body glutamine rate of appearance was 5.8 +/- 1.0 micromol x kg (-1) body wt x min (-1), and whole-body clearance was 19.3 +/- 3.3 mL x kg(-1) x min (-1). Despite the low intramuscular glutamine concentration in the patients, the rate of unidirectional outward transport from skeletal muscle into venous blood (1.1. +/- 0.2 micromol x 100 mL x leg(-1) x min(-1)) was similar to that observed in healthy volunteers (1.6 +/- 0.2 mol x 100 mL x leg(-1) x min(-1)); intramuscular synthesis was 2.7 +/- 0.9 micromol x 100 mL x leg(-1) x min(-1) compared with a normal value of 0.6 +/- 0.06 micromol x 100 mL x leg(-1) x min(-1). Net balance across the leg was normal. CONCLUSIONS: The depletion of intramuscular glutamine in critically ill patients is not due to an impairment of the rate of synthesis. In fact, accelerated glutamine production cannot maintain normal intramuscular glutamine levels because of accelerated outward transport.
B Mittendorfer; D C Gore; D N Herndon; R R Wolfe
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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:  JPEN. Journal of parenteral and enteral nutrition     Volume:  23     ISSN:  0148-6071     ISO Abbreviation:  JPEN J Parenter Enteral Nutr     Publication Date:    1999 Sep-Oct
Date Detail:
Created Date:  1999-10-21     Completed Date:  1999-10-21     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7804134     Medline TA:  JPEN J Parenter Enteral Nutr     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  243-50; discussion 250-2     Citation Subset:  IM    
Department of Surgery, The University of Texas Medical Branch at Galveston, USA.
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MeSH Terms
Burns / metabolism,  therapy
Critical Illness*
Femoral Artery
Femoral Vein
Glutamine / biosynthesis*,  blood,  metabolism
Intensive Care
Ketoglutaric Acids / administration & dosage,  blood,  metabolism
Muscle, Skeletal / metabolism*
Grant Support
Reg. No./Substance:
0/Ketoglutaric Acids; 328-50-7/alpha-ketoglutaric acid; 56-85-9/Glutamine

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