Document Detail

Somatotropin-induced amino acid conservation in pigs involves differential regulation of liver and gut urea cycle enzyme activity.
MedLine Citation:
PMID:  11773509     Owner:  NLM     Status:  MEDLINE    
Somatotropin (ST) treatment promotes animal growth and allows for the conservation of amino acids by increasing nitrogen retention and reducing ureagenesis and amino acid oxidation. To determine whether the improvement in amino acid conservation with ST treatment involves regulation of urea cycle enzyme activities in both liver and intestine, growing swine were treated with either ST (150 microg x kg(-1) x d(-1)) or saline for 7 d. Fully fed pigs (n = 20) were infused intravenously for 2 h with NaH(13)CO(3) followed by a 4-h intraduodenal infusion of [1-(13)C]phenylalanine. Arterial and portal venous blood and breath samples were obtained at baseline and steady-state conditions for measurement of amino acid and blood urea nitrogen (BUN) concentrations and whole-body phenylalanine oxidation. Urea cycle enzyme activities were determined in liver and jejunum. ST decreased BUN (-46%), arterial (-34%) and portal venous (-43%) amino acid concentrations and whole-body phenylalanine oxidation (-30%). The activities of carbamoylphosphate synthase-I (-45%), argininosuccinate synthase (-38%), argininosuccinate lyase (-23%), arginase (-27%), and glutaminase (-18%), but not of ornithine carbamoyltransferase, ornithine aminotransferase, or glutamate dehydrogenase were reduced in liver of ST-treated pigs. ST slightly increased intestinal activity of glutaminase (+9%) but did not affect that of any other enzymes. ST decreased hepatic, but increased jejunal, N-acetylglutamate (an essential allosteric activator of carbamoylphosphate synthase-I; -26% and +32%, respectively) and carbamoylphosphate (a substrate for ornithine carbamoyltransferase; -20% and +28%, respectively) content. These results demonstrate that the reduced amino acid catabolism with ST treatment in growing pigs involves a reduction in hepatic urea cycle enzyme activities. The effect of ST treatment on porcine urea cycle enzymes is tissue-specific and is associated with a reduction in substrate availability for hepatic ureagenesis.
Jill A Bush; Guoyao Wu; Agus Suryawan; Hanh V Nguyen; Teresa A Davis
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of nutrition     Volume:  132     ISSN:  0022-3166     ISO Abbreviation:  J. Nutr.     Publication Date:  2002 Jan 
Date Detail:
Created Date:  2002-01-04     Completed Date:  2002-02-05     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0404243     Medline TA:  J Nutr     Country:  United States    
Other Details:
Languages:  eng     Pagination:  59-67     Citation Subset:  IM    
U.S. Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
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MeSH Terms
Amino Acids / blood*,  metabolism
Ammonia / blood
Bicarbonates / blood
Blood Urea Nitrogen
Body Weight / drug effects
Breath Tests
Carbamyl Phosphate / metabolism
Carbon Isotopes / diagnostic use
Glutamates / metabolism
Growth Hormone / pharmacology*
Jejunum / enzymology*
Liver / enzymology*
Nitrogen / metabolism
Phenylalanine / metabolism
Random Allocation
Substrate Specificity
Swine / blood,  growth & development*
Urea / metabolism
Grant Support
Reg. No./Substance:
0/Amino Acids; 0/Bicarbonates; 0/Carbon Isotopes; 0/Glutamates; 1188-37-0/N-acetylglutamate; 57-13-6/Urea; 590-55-6/Carbamyl Phosphate; 63-91-2/Phenylalanine; 7664-41-7/Ammonia; 7727-37-9/Nitrogen; 9002-72-6/Growth Hormone

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

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