Difference between revisions of "Boushel 2013 Int J Biochem Cell Biol"
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|abstract=Muscle mitochondrial respiratory capacity measured ''ex vivo'' provides a physiological reference to assess cellular oxidative capacity as a component in the oxygen cascade in vivo. In this article, the magnitude of muscle blood flow and oxygen uptake during exercise involving a small-to-large fraction of the body mass will be discussed in relation to mitochondrial capacity measured ''ex vivo''. These analyses reveal that as the mass of muscle engaged in exercise increases from one-leg knee extension, to 2-arm cranking, to 2-leg cycling and x-country skiing, the magnitude of blood flow and oxygen delivery decrease. Accordingly, a 2-fold higher oxygen delivery and oxygen uptake per unit muscle mass are seen ''in vivo'' during 1-leg exercise compared to 2-leg cycling indicating a significant limitation of the circulation during exercise with a large muscle mass. This analysis also reveals that mitochondrial capacity measured ''ex vivo'' underestimates the maximal ''in vivo'' oxygen uptake of muscle by up to ∼2-fold. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy. | |abstract=Muscle mitochondrial respiratory capacity measured ''ex vivo'' provides a physiological reference to assess cellular oxidative capacity as a component in the oxygen cascade ''in vivo''. In this article, the magnitude of muscle blood flow and oxygen uptake during exercise involving a small-to-large fraction of the body mass will be discussed in relation to mitochondrial capacity measured ''ex vivo''. These analyses reveal that as the mass of muscle engaged in exercise increases from one-leg knee extension, to 2-arm cranking, to 2-leg cycling and x-country skiing, the magnitude of blood flow and oxygen delivery decrease. Accordingly, a 2-fold higher oxygen delivery and oxygen uptake per unit muscle mass are seen ''in vivo'' during 1-leg exercise compared to 2-leg cycling indicating a significant limitation of the circulation during exercise with a large muscle mass. This analysis also reveals that mitochondrial capacity measured ''ex vivo'' underestimates the maximal ''in vivo'' oxygen uptake of muscle by up to ∼2-fold. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy. | ||
|keywords=O2 delivery; Oxidative phosphorylation; Exercise | |||
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Revision as of 14:44, 31 March 2015
| Boushel RC, Saltin B (2013) Ex vivo measures of muscle mitochondrial capacity reveal quantitative limits of oxygen delivery by the circulation during exercise. Int J Biochem Cell Biol 45:68-75. |
Boushel RC, Saltin B (2013) Int J Biochem Cell Biol
Abstract: Muscle mitochondrial respiratory capacity measured ex vivo provides a physiological reference to assess cellular oxidative capacity as a component in the oxygen cascade in vivo. In this article, the magnitude of muscle blood flow and oxygen uptake during exercise involving a small-to-large fraction of the body mass will be discussed in relation to mitochondrial capacity measured ex vivo. These analyses reveal that as the mass of muscle engaged in exercise increases from one-leg knee extension, to 2-arm cranking, to 2-leg cycling and x-country skiing, the magnitude of blood flow and oxygen delivery decrease. Accordingly, a 2-fold higher oxygen delivery and oxygen uptake per unit muscle mass are seen in vivo during 1-leg exercise compared to 2-leg cycling indicating a significant limitation of the circulation during exercise with a large muscle mass. This analysis also reveals that mitochondrial capacity measured ex vivo underestimates the maximal in vivo oxygen uptake of muscle by up to ∼2-fold. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy. • Keywords: O2 delivery; Oxidative phosphorylation; Exercise
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Comment on Figures 2 and 3
- Fig. 2: The mitochondrial pathways shown in Fig. 2 are a direct copy of a figure made available by Erich Gnaiger to Robert Boushel (and A.N.) in the context of introductory O2k-Workshops and collaborations starting in 2003/2004. The figure is a preliminary and erroneous version of the published Figure (Gnaiger 2007), since FADH2 is shown on a comparable level with NADH, a frequently observed textbook error. The corrected figure (with Succinate and NADH on a comparable level) was published in 2007 and 2009 (Gnaiger 2007, 2009). The propagation of an erroneous figure is unfortunate, and the correct citation is missing in Boushel and Saltin (2012).
- Gnaiger E, ed (2007) Mitochondrial Pathways and Respiratory Control. OROBOROS MiPNet Publications, Innsbruck: 96 pp. Electronic 1st edition, ISBN: 978-3-9502399-0-4 - http://www.oroboros.at/?MiPNet-Publications
- Gnaiger E (2007-2001) Mitochondrial pathways through Complexes I&II: Convergent electron transport at the Q-junction and additive effect of substrate combinations. Mitochondr Physiol Network 12.12. - http://www.oroboros.at/?C1-and-2
- Fig. 3: No permission was ever given to reproduce the figure in this article. A proper citation is:
- Gnaiger E, Wright-Paradis C, Sondergaard H, Lundby C, Calbet JA, Saltin B, Helge J, Boushel R (2005) High-resolution respirometry in small biopsies of human muscle: correlations with body mass index and age. Mitochondr Physiol Network 10.9: 14-15. http://www.mitophysiology.org/?gnaigere.
- A clarification is required on the journal level.
- This comment is added here in the spirit of Gentle Science.
- Erich Gnaiger (2012-11-14)
Clarification by RC Boushel
- I have .. decided to write to the editor of IJBCB and retract our paper from the Journal. .. with sincere apologies, Rob (2012-11-15).
- I fully agree and will request .. to have these figures removed Rob (2012-11-17).
