Document Detail


Continuous measurement of 13C16O2 production from [13C]pyruvate by intact liver mitochondria: effect of HCO3-.
MedLine Citation:
PMID:  8772434     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We have measured continuously the production of mass 45 CO2(13C16O2) from 13C-labeled pyruvate in a guinea pig liver mitochondrial suspension and simultaneously the O2 consumption at 37 degrees C and pH 7.4. The reactions took place in a closed 3-ml volume, stirred, thermoregulated chamber separated from the ion source of a mass spectrometer by a gas-permeable membrane that permitted recording the mass peaks of any gas dissolved in the reaction mixture with a response time as fast as 3 s. If the pyruvate was labeled on C-2, no 13C16O2 was formed, even after 1 h, indicating that C-2 and C-3 were not metabolized in the citric acid cycle. We found that production of 13C16O2 was five times greater in the presence of 25 mM HCO3- than in its absence. A probable mechanism of this CO2/HCO3- effect is carboxylation of pyruvate to oxaloacetate, which would react with acetyl CoA to form citrate and with NADH to form malate, thus removing two major inhibitors of pyruvate dehydrogenase. We conclude that CO2/HCO3- has a potent and hitherto unappreciated regulatory effect on liver pyruvate dehydrogenase.
Authors:
Y Ono; L Lin; B T Storey; Y Taguchi; S J Dodgson; R E Forster
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  270     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1996 Jan 
Date Detail:
Created Date:  1996-12-19     Completed Date:  1996-12-19     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  C98-106     Citation Subset:  IM    
Affiliation:
Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia 19104, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Bicarbonates / pharmacology*
Carbon Dioxide / metabolism*
Carbon Isotopes
Decarboxylation
Guinea Pigs
Hydrogen-Ion Concentration
Ions
Mitochondria, Liver / metabolism*
Oxygen Consumption
Pyruvic Acid / metabolism*
Temperature
Grant Support
ID/Acronym/Agency:
HL-47815/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Bicarbonates; 0/Carbon Isotopes; 0/Ions; 124-38-9/Carbon Dioxide; 127-17-3/Pyruvic Acid

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


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