Document Detail


Influence of lysine on urea cycle activity and orotate formation in the isolated perfused rat liver.
MedLine Citation:
PMID:  3924076     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
There was a reversible inhibition of urea formation in the perfused rat liver caused by 2.25-27 mM lysine acting with a Ki of 10.8 mM in competition with ornithine. Urea formation in the presence of inhibitory concentrations of lysine ranged between 2.3 and 2.9 mumol X min-1 X (g, liver wet)-1 after addition of 1 mM of citrulline, argininosuccinate or arginine, whereas it amounted to 0.5 mumol X min-1 X (g, liver wet)-1 after addition of ornithine, showing that lysine inhibited the urea cycle between ornithine and citrulline. There was a rise of basal orotate formation of 0.03 +/- 0.02 mumol X h-1 X (g, liver wet)-1 towards a maximum of 0.6 +/- 0.04 mumol X h-1 X (g, liver wet)-1 after addition of 13.5 mM lysine, provided orotate utilization was blocked with allopurinol. Maximal rates of orotate formation were reached when ammonium concentrations exceeded 1 mM. We conclude that an inhibition of urea synthesis and a rise of orotate formation are caused by lysine in the isolated liver in vitro at rates observed in vivo. Hence, these metabolic alterations observed in the whole animal are most probably due to changes of liver metabolism.
Authors:
M de Vrese; C A Barth
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Biological chemistry Hoppe-Seyler     Volume:  366     ISSN:  0177-3593     ISO Abbreviation:  Biol. Chem. Hoppe-Seyler     Publication Date:  1985 May 
Date Detail:
Created Date:  1985-08-22     Completed Date:  1985-08-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8503054     Medline TA:  Biol Chem Hoppe Seyler     Country:  GERMANY, WEST    
Other Details:
Languages:  eng     Pagination:  455-61     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Ammonia / pharmacology
Animals
Kinetics
Liver / drug effects,  metabolism*
Lysine / pharmacology*
Male
Ornithine / pharmacology
Orotic Acid / biosynthesis*
Perfusion
Rats
Rats, Inbred Strains
Urea / metabolism*
Chemical
Reg. No./Substance:
56-87-1/Lysine; 57-13-6/Urea; 65-86-1/Orotic Acid; 7006-33-9/Ornithine; 7664-41-7/Ammonia

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


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