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Glutamine metabolism: Role in acid-base balance*.
MedLine Citation:
PMID:  21706743     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
The intent of this review is to provide a broad overview of the interorgan metabolism of glutamine and to discuss in more detail its role in acid-base balance. Muscle, adipose tissue, and the lungs are the primary sites of glutamine synthesis and release. During normal acid-base balance, the small intestine and the liver are the major sites of glutamine utilization. The periportal hepatocytes catabolize glutamine and convert ammonium and bicarbonate ions to urea. In contrast, the perivenous hepatocytes are capable of synthesizing glutamine. During metabolic acidosis, the kidney becomes the major site of glutamine extraction and catabolism. This process generates ammonium ions that are excreted in the urine to facilitate the excretion of acids and bicarbonate ions that are transported to the blood to partially compensate the acidosis. The increased renal extraction of glutamine is balanced by an increased release from muscle and liver and by a decreased utilization in the intestine. During chronic acidosis, this adaptation is sustained, in part, by increased renal expression of genes that encode various transport proteins and key enzymes of glutamine metabolism. The increased levels of phosphoenolpyruvate carboxykinase result from increased transcription, while the increase in glutaminase and glutamate dehydrogenase activities result from stabilization of their respective mRNAs. Where feasible, this review draws upon data obtained from studies in humans. Studies conducted in model animals are discussed where available data from humans is either lacking or not firmly established. Because there are quantitative differences in tissue utilization and synthesis of glutamine in different mammals, the review will focus more on common principles than on quantification.
Authors:
Lynn Taylor; Norman P Curthoys
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Biochemistry and molecular biology education : a bimonthly publication of the International Union of Biochemistry and Molecular Biology     Volume:  32     ISSN:  1470-8175     ISO Abbreviation:  Biochem Mol Biol Educ     Publication Date:  2004 Sep 
Date Detail:
Created Date:  2011-06-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100970605     Medline TA:  Biochem Mol Biol Educ     Country:  United States    
Other Details:
Languages:  eng     Pagination:  291-304     Citation Subset:  -    
Copyright Information:
Copyright © 2004 International Union of Biochemistry and Molecular Biology, Inc.
Affiliation:
Department of Biochemistry and Molecular Biology Colorado State University, Fort Collins, CO 80523-1870.
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