| Fatty acid oxidation is directly regulated by carbohydrate metabolism during exercise. | |
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MedLine Citation:
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PMID: 9277379 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We determined whether increased glycolytic flux from hyperglycemia and hyperinsulinemia directly reduces fatty acid oxidation during exercise. Fatty acid oxidation rates were measured during constant-rate intravenous infusion of trace amounts of a long-chain fatty acid ([1-13C]palmitate; Pal) vs. a medium-chain fatty acid ([1-13C]octanoate; Oct). Six endurance-trained men cycled for 40 min at 50% of maximal O2 uptake 1) after an overnight fast ("fasting") and 2) after ingestion of 1.4 g/kg of glucose at 60 min and again 10 min before exercise (Glc). Glc caused hyperinsulinemia, a preexercise blood glucose of 6 mM, and a 34% reduction in total fat oxidation during exercise due to an approximately equal reduction in oxidation of plasma-free fatty acids (FFA) and intramuscular triglycerides (all P < 0.05). Oxidation of Pal was significantly reduced during Glc compared with fast (i.e., 70.0 +/- 4.1 vs. 86.0 +/- 1.9% of tracer infusion rate; P < 0.05). However, Glc had no effect on Oct oxidation, which is apparently not limited by mitochondrial transport. Furthermore, Glc reduced plasma FFA appearance 36% (P < 0.05), indicating a coordination of effects on adipose tissue and muscle. In summary, substrate oxidation during exercise can be regulated by increased glycolytic flux that is accompanied by a direct inhibition of long-chain fatty acid oxidation. These observations indicate that carbohydrate availability can directly regulate fat oxidation during exercise. |
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Authors:
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E F Coyle; A E Jeukendrup; A J Wagenmakers; W H Saris |
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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 American journal of physiology Volume: 273 ISSN: 0002-9513 ISO Abbreviation: Am. J. Physiol. Publication Date: 1997 Aug |
Date Detail:
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Created Date: 1997-09-24 Completed Date: 1997-09-24 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0370511 Medline TA: Am J Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: E268-75 Citation Subset: IM |
Affiliation:
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Department of Human Biology, University of Limburg, Maastricht, The Netherlands. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adipose Tissue
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anatomy & histology Adult Blood Glucose / analysis Carbohydrate Metabolism* Carbon Dioxide Exercise* Fatty Acids / metabolism* Fatty Acids, Nonesterified / blood Humans Insulin / blood Male Muscles / metabolism Octanoic Acids / metabolism Oxidation-Reduction Palmitates / metabolism Respiration Triglycerides / metabolism |
| Chemical | |
Reg. No./Substance:
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0/Blood Glucose; 0/Fatty Acids; 0/Fatty Acids, Nonesterified; 0/Octanoic Acids; 0/Palmitates; 0/Triglycerides; 11061-68-0/Insulin; 124-07-2/caprylic acid; 124-38-9/Carbon Dioxide |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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