| Hyperoxia decreases muscle glycogenolysis, lactate production, and lactate efflux during steady-state exercise. | |
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MedLine Citation:
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PMID: 16403777 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The aim of this study was to determine whether the decreased muscle and blood lactate during exercise with hyperoxia (60% inspired O2) vs. room air is due to decreased muscle glycogenolysis, leading to decreased pyruvate and lactate production and efflux. We measured pyruvate oxidation via PDH, muscle pyruvate and lactate accumulation, and lactate and pyruvate efflux to estimate total pyruvate and lactate production during exercise. We hypothesized that 60% O2 would decrease muscle glycogenolysis, resulting in decreased pyruvate and lactate contents, leading to decreased muscle pyruvate and lactate release with no change in PDH activity. Seven active male subjects cycled for 40 min at 70% VO2 peak on two occasions when breathing 21 or 60% O2. Arterial and femoral venous blood samples and blood flow measurements were obtained throughout exercise, and muscle biopsies were taken at rest and after 10, 20, and 40 min of exercise. Hyperoxia had no effect on leg O2 delivery, O2 uptake, or RQ during exercise. Muscle glycogenolysis was reduced by 16% with hyperoxia (267 +/- 19 vs. 317 +/- 21 mmol/kg dry wt), translating into a significant, 15% reduction in total pyruvate production over the 40-min exercise period. Decreased pyruvate production during hyperoxia had no effect on PDH activity (pyruvate oxidation) but significantly decreased lactate accumulation (60%: 22.6 +/- 6.4 vs. 21%: 31.3 +/- 8.7 mmol/kg dry wt), lactate efflux, and total lactate production over 40 min of cycling. Decreased glycogenolysis in hyperoxia was related to an approximately 44% lower epinephrine concentration and an attenuated accumulation of potent phosphorylase activators ADPf and AMPf during exercise. Greater phosphorylation potential during hyperoxia was related to a significantly diminished rate of PCr utilization. The tighter metabolic match between pyruvate production and oxidation resulted in a decrease in total lactate production and efflux over 40 min of exercise during hyperoxia. |
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Authors:
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Trent Stellingwerff; Paul J Leblanc; Melanie G Hollidge; George J F Heigenhauser; Lawrence L Spriet |
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Publication Detail:
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Type: Clinical Trial; In Vitro; Journal Article; Research Support, Non-U.S. Gov't Date: 2006-01-10 |
Journal Detail:
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Title: American journal of physiology. Endocrinology and metabolism Volume: 290 ISSN: 0193-1849 ISO Abbreviation: Am. J. Physiol. Endocrinol. Metab. Publication Date: 2006 Jun |
Date Detail:
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Created Date: 2006-05-09 Completed Date: 2006-07-13 Revised Date: 2007-02-16 |
Medline Journal Info:
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Nlm Unique ID: 100901226 Medline TA: Am J Physiol Endocrinol Metab Country: United States |
Other Details:
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Languages: eng Pagination: E1180-90 Citation Subset: IM |
Affiliation:
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Dept. of Human Health and Nutritional Sciences, Univ. of Guelph, Guelph, ON, N1G 2W1, Canada. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Blood Gas Analysis Exercise / physiology* Glucose / metabolism Glycogenolysis* Humans Hyperoxia / metabolism* Lactic Acid / blood, metabolism* Leg / blood supply Male Muscle, Skeletal / anatomy & histology, metabolism* Pyruvate Dehydrogenase (Lipoamide) / metabolism Pyruvic Acid / blood, metabolism Time Factors |
| Chemical | |
Reg. No./Substance:
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127-17-3/Pyruvic Acid; 50-21-5/Lactic Acid; 50-99-7/Glucose; EC 1.2.4.1/Pyruvate Dehydrogenase (Lipoamide); EC 1.2.4.1/pyruvate dehydrogenase E1alpha subunit |
| Comments/Corrections | |
Comment In:
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Am J Physiol Endocrinol Metab. 2007 Jan;292(1):E366
[PMID:
16926378
]
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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