| The regulation of hepatic carbon flux by pyruvate dehydrogenase and pyruvate dehydrogenase kinase during long-term food restriction. | |
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MedLine Citation:
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PMID: 8250846 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The present study investigated the effects of chronic food restriction (achieved by limiting access to food to 2 h daily for up to 8 weeks) on the activity of the active form of pyruvate dehydrogenase (PDHa) in liver. Accelerated and exaggerated activation of hepatic PDH in response to a meal, previously demonstrated to occur within 10 days of food restriction, was demonstrated to persist for 4 and 8 weeks of food restriction, despite a food intake of only 50-60% of controls. Activation of hepatic PDH during feeding in rats subjected to food restriction for 4 weeks was dependent on continued food intake. As a consequence, hepatic PDHa activities in food-restricted rats were suppressed relative to controls for 19 h of the 24 h daily cycle. Curve-fitting by second-order polynomial regression analysis demonstrated a significant positive correlation between hepatic PDHa activity and lipogenic rate over the range of PDHa activities observed during the 2 h feeding period. Increased lipogenesis during feeding in food-restricted rats was not at the expense of hepatic glycogen synthesis or deposition; measurement of concurrent rates of glycogenesis and lipogenesis revealed simultaneous flux through both pathways, but specific activation of lipogenesis. The accelerated re-activation of hepatic PDH observed within 1 h of feeding in rats subjected to 4 weeks of food restriction was facilitated by a failure of the 22 h interprandial fasting period to induce a stable increase in hepatic PDH kinase activity. The present study indicates differential regulation of hepatic PDH kinase activity during periods of food withdrawal between food-restricted rats and starved/re-fed control rats. Such regulation occupies a critical role in determining the rate of activation of hepatic PDH during feeding. In turn, increased activity of hepatic PDHa during feeding in food-restricted rats bears a close positive relationship with hepatic lipogenic rate. |
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Authors:
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M C Sugden; R M Grimshaw; M J Holness |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Biochemical journal Volume: 296 ( Pt 1) ISSN: 0264-6021 ISO Abbreviation: Biochem. J. Publication Date: 1993 Nov |
Date Detail:
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Created Date: 1993-12-29 Completed Date: 1993-12-29 Revised Date: 2009-11-19 |
Medline Journal Info:
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Nlm Unique ID: 2984726R Medline TA: Biochem J Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 217-23 Citation Subset: IM |
Affiliation:
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Department of Biochemistry, Faculty of Basic Medical Sciences, Queen Mary & Westfield College, University of London, U.K. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Diet* Diet, Reducing Female Lipids / biosynthesis Liver / enzymology, metabolism* Liver Glycogen / metabolism* Protein Kinases / metabolism* Protein-Serine-Threonine Kinases Pyruvate Dehydrogenase Complex / metabolism* Rats Rats, Wistar Regression Analysis Time Factors |
| Chemical | |
Reg. No./Substance:
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0/Lipids; 0/Liver Glycogen; 0/Pyruvate Dehydrogenase Complex; EC 2.7.-/Protein Kinases; EC 2.7.11.1/Protein-Serine-Threonine Kinases; EC 2.7.11.2/pyruvate dehydrogenase (acetyl-transferring) kinase |
| Comments/Corrections | |
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