Document Detail


Utilization for protein synthesis of 2-ketoisocaproate relative to utilization of leucine, as estimated from exhalation of labelled CO2.
MedLine Citation:
PMID:  3138058     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
1. We have previously shown that the ratio (RWBP) of incorporation of label from 2-ketoisocaproate (KIC) into the leucine of whole-body protein to the simultaneous incorporation of label from leucine itself into protein is a measure of the nutritional efficiency of KIC as a substitute for leucine. 2. In order to determine whether RWBP can be estimated indirectly from measurement of labelled CO2 excretion, rats were injected orally or intravenously with [4,5-3H]leucine and either [1-14C]leucine or [1-14C]KIC. Expired CO2 was collected for 6 h. 3. The results show that 9-14% of KIC underwent first-pass oxidation after oral administration. When isotopes were given intravenously, the mean rate of excretion of 14CO2 from KIC, after 20 min, remained 1.8 times the mean rate of excretion of 14CO2 from leucine. 4. Mean RWBP, measured in whole-body protein in rats given isotopes orally or intravenously along with small or large doses of carriers, was the same as mean RWBP estimated from mean cumulative CO2 excretion. 5. We conclude (1) that nutritional efficiency of KIC relative to leucine can be estimated from measurement of labelled CO2 excretion, and (2) that the relative inefficiency of KIC as a substitute for leucine in the rat is attributable to first-pass oxidation of 9-14% (when given orally) and 80% greater susceptibility to systemic oxidation than leucine.
Authors:
K Imura; T Shiota; L M Swain; M Walser
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Clinical science (London, England : 1979)     Volume:  75     ISSN:  0143-5221     ISO Abbreviation:  Clin. Sci.     Publication Date:  1988 Sep 
Date Detail:
Created Date:  1988-10-24     Completed Date:  1988-10-24     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7905731     Medline TA:  Clin Sci (Lond)     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  301-7     Citation Subset:  IM    
Affiliation:
Department of Pharmacology and Molecular Science, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205.
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MeSH Terms
Descriptor/Qualifier:
Animals
Carbon Dioxide / analysis
Keto Acids / pharmacokinetics*
Leucine / pharmacokinetics*
Male
Oxidation-Reduction
Protein Biosynthesis*
Rats
Rats, Inbred Strains
Grant Support
ID/Acronym/Agency:
5-R01-DK-32009-03/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Keto Acids; 124-38-9/Carbon Dioxide; 61-90-5/Leucine; 816-66-0/alpha-ketoisocaproic acid

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


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