| Mitochondrial function during heavy exercise. | |
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MedLine Citation:
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PMID: 7837955 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Maximal rates, coupling, and control of oxidative phosphorylation were studied in isolated skeletal muscle mitochondria from rat and rabbit. Mitochondria were incubated under various conditions of temperature, pH, and substrate availability. A 20% decrease in coupling (ADP/O) was observed at 43 degrees C as compared to 37 degrees C in rat mixed skeletal muscle mitochondria. Changes in pH from 7.00 to 6.20 affected neither coupling nor maximal (state 3) respiration rates. Changing the substrate supply from pyruvate to palmitoyl-carnitine (+ malate) did not alter ADP/O, but markedly degraded the energy state sustained at submaximal ATP turnover. Thus, carbohydrate depletion may be associated with inhibition of contractile function and the recruitment of less economical higher threshold motor units. State 3 respiration of mitochondria from rabbit Type IIb fibers oxidizing pyruvate+malate+alpha-glycerophosphate was 27% higher than that of mitochondria from Type I rabbit skeletal muscle. However, the ADP/O ratio in the Type IIb preparation was 18% lower. The experimental findings suggest that temperature, substrate supply, and energetic differences between slow twitch and fast twitch motor units may impact the economy of mitochondrial oxygen utilization during heavy aerobic exercise, and thus contribute to the slow component of oxygen uptake. |
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Authors:
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W T Willis; M R Jackman |
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Publication Detail:
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Type: In Vitro; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Medicine and science in sports and exercise Volume: 26 ISSN: 0195-9131 ISO Abbreviation: Med Sci Sports Exerc Publication Date: 1994 Nov |
Date Detail:
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Created Date: 1995-02-27 Completed Date: 1995-02-27 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 8005433 Medline TA: Med Sci Sports Exerc Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1347-53 Citation Subset: IM; S |
Affiliation:
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Exercise and Sport Research Institute, Arizona State University, Tempe 85287-0404. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Body Temperature / physiology Hydrogen-Ion Concentration Mitochondria, Muscle / metabolism*, physiology Oxygen Consumption / physiology Physical Exertion / physiology* Rabbits Rats |
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