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dc.contributor.authorLayec, G.
dc.contributor.authorHaseler, Luke
dc.contributor.authorTrinity, J.
dc.contributor.authorHart, C.
dc.contributor.authorLiu, X.
dc.contributor.authorFur, Y.
dc.contributor.authorJeong, E.
dc.contributor.authorRichardson, R.
dc.identifier.citationLayec, G. and Haseler, L. and Trinity, J. and Hart, C. and Liu, X. and Fur, Y. and Jeong, E. et al. 2013. Mitochondrial function and increased convective O2 transport: Implications for the assessment of mitochondrial respiration in vivo. Journal of Applied Physiology. 115 (6): pp. 803-811.

Although phosphorus magnetic resonance spectroscopy ( 31 P-MRS)- based evidence suggests that in vivo peak mitochondrial respiration rate in young untrained adults is limited by the intrinsic mitochondrial capacity of ATP synthesis, it remains unknown whether a large, locally targeted increase in convective O2 delivery would alter this interpretation. Consequently, we examined the effect of superimposing reactive hyperemia (RH), induced by a period of brief ischemia during the last minute of exercise, on oxygen delivery and mitochondrial function in the calf muscle of nine young adults compared with free-flow conditions (FF). To this aim, we used an integrative experimental approach combining 31 P-MRS, Doppler ultrasound imaging, and near-infrared spectroscopy. Limb blood flow [area under the curve (AUC), 1.4 ± 0.8 liters in FF and 2.5 ± 0.3 liters in RH, P < 0.01] and convective O2 delivery (AUC, 0.30 ± 0.16 liters in FF and 0.54 ± 0.05 liters in RH, P < 0.01), were significantly increased in RH compared with FF. RH was also associated with significantly higher capillary blood flow (P < 0.05) and faster tissue reoxygenation mean response times (70 ± 15 s in FF and 24 ± 15 s in RH, P < 0.05). This resulted in a 43% increase in estimated peak mitochondrial ATP synthesis rate (29 ± 13 mM/min in FF and 41 ± 14 mM/min in RH, P < 0.05) whereas the phosphocreatine (PCr) recovery time constant in RH was not significantly different (P = 0.22). This comprehensive assessment of local skeletal muscle O2 availability and utilization in untrained subjects reveals that mitochondrial function, assessed in vivo by 31 P-MRS, is limited by convective O2 delivery rather than an intrinsic mitochondrial limitation. © 2013 the American Physiological Society.

dc.publisherThe American Physiological Society
dc.titleMitochondrial function and increased convective O2 transport: Implications for the assessment of mitochondrial respiration in vivo
dc.typeJournal Article
dcterms.source.titleJournal of Applied Physiology
curtin.departmentSchool of Physiotherapy and Exercise Science
curtin.accessStatusOpen access via publisher

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