Mitochondrial function and increased convective O2 transport: Implications for the assessment of mitochondrial respiration in vivo
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 co...
| Main Authors: | , , , , , , , |
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| Format: | Journal Article |
| Published: |
The American Physiological Society
2013
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| Online Access: | http://hdl.handle.net/20.500.11937/58274 |
| _version_ | 1848760218622623744 |
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| author | Layec, G. Haseler, Luke Trinity, J. Hart, C. Liu, X. Fur, Y. Jeong, E. Richardson, R. |
| author_facet | Layec, G. Haseler, Luke Trinity, J. Hart, C. Liu, X. Fur, Y. Jeong, E. Richardson, R. |
| author_sort | Layec, G. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | 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. |
| first_indexed | 2025-11-14T10:12:17Z |
| format | Journal Article |
| id | curtin-20.500.11937-58274 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:12:17Z |
| publishDate | 2013 |
| publisher | The American Physiological Society |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-582742023-02-22T06:24:20Z Mitochondrial function and increased convective O2 transport: Implications for the assessment of mitochondrial respiration in vivo Layec, G. Haseler, Luke Trinity, J. Hart, C. Liu, X. Fur, Y. Jeong, E. Richardson, R. 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. 2013 Journal Article http://hdl.handle.net/20.500.11937/58274 10.1152/japplphysiol.00257.2013 The American Physiological Society unknown |
| spellingShingle | Layec, G. Haseler, Luke Trinity, J. Hart, C. Liu, X. Fur, Y. Jeong, E. Richardson, R. Mitochondrial function and increased convective O2 transport: Implications for the assessment of mitochondrial respiration in vivo |
| title | Mitochondrial function and increased convective O2 transport: Implications for the assessment of mitochondrial respiration in vivo |
| title_full | Mitochondrial function and increased convective O2 transport: Implications for the assessment of mitochondrial respiration in vivo |
| title_fullStr | Mitochondrial function and increased convective O2 transport: Implications for the assessment of mitochondrial respiration in vivo |
| title_full_unstemmed | Mitochondrial function and increased convective O2 transport: Implications for the assessment of mitochondrial respiration in vivo |
| title_short | Mitochondrial function and increased convective O2 transport: Implications for the assessment of mitochondrial respiration in vivo |
| title_sort | mitochondrial function and increased convective o2 transport: implications for the assessment of mitochondrial respiration in vivo |
| url | http://hdl.handle.net/20.500.11937/58274 |