Document Detail


Adrenergic inhibition of branched-chain 2-oxo acid dehydrogenase in rat diaphragm muscle in vitro.
MedLine Citation:
PMID:  6140003     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In theory, the complete oxidation to CO2 of amino acids that are metabolized by conversion into tricarboxylic acid-cycle intermediates may proceed via their conversion into acetyl-CoA. The possible adrenergic modulation of this oxidative pathway was investigated in isolated hemidiaphragms from 40 h-starved rats. Adrenaline (5.5 microM), phenylephrine (0.49 mM) and dibutyryl cyclic AMP (10 microM) inhibited 14CO2 production from 3 mM-[U-14C]valine by 35%, 28% and 19% respectively. At the same time, these agents stimulated glycogen mobilization (measured as a decrease in glycogen content) and glycolysis (measured as lactate release). Adrenaline, phenylephrine and dibutyryl cyclic AMP did not inhibit 14CO2 production from 3 mM-[U-14C]aspartate or 3 mM-[U-14C]glutamate, although, as in the presence of valine, the agents stimulated glycogen mobilization and glycolysis. The rate of proteolysis (measured as tyrosine release in the presence of cycloheximide) was not changed by adrenaline. The data indicate that the adrenergic inhibition of 14CO2 production from [U-14C]valine was not a consequence of radiolabel dilution. Inhibition was apparently specific for branched-chain amino acid metabolism in that the adrenergic agonists also inhibited 14CO2 production from [1-14C]valine, [1-14C]leucine and [U-14C]isoleucine. Since 14CO2 production from the 1-14C-labelled substrates is a specific measure of decarboxylation in the reaction catalysed by the branched-chain 2-oxo acid dehydrogenase complex, it is at this site that the adrenergic agents are concluded to act.
Authors:
T N Palmer; M A Caldecourt; M C Sugden
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  The Biochemical journal     Volume:  216     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  1983 Oct 
Date Detail:
Created Date:  1984-01-07     Completed Date:  1984-01-07     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  63-70     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
Animals
Aspartic Acid / metabolism
Bucladesine / pharmacology*
Epinephrine / pharmacology*
Glutamates / metabolism
Glutamic Acid
Ketone Oxidoreductases / antagonists & inhibitors*
Male
Multienzyme Complexes / antagonists & inhibitors*
Muscles / drug effects,  enzymology*
Oxidation-Reduction
Phenylephrine / pharmacology*
Rats
Rats, Inbred Strains
Valine / metabolism
Chemical
Reg. No./Substance:
0/Glutamates; 0/Multienzyme Complexes; 362-74-3/Bucladesine; 51-43-4/Epinephrine; 56-84-8/Aspartic Acid; 56-86-0/Glutamic Acid; 59-42-7/Phenylephrine; 7004-03-7/Valine; EC 1.2.-/Ketone Oxidoreductases; EC 1.2.4.4/3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
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