Difference between revisions of "Scott 2009 Am J Physiol Regul Integr Comp Physiol"
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|journal=Am J Physiol Regul Integr Comp Physiol | |journal=Am J Physiol Regul Integr Comp Physiol | ||
|abstract=Bar-headed geese fly at altitudes of up to 9,000 m on their biannual migration over the Himalayas. To determine whether the flight muscle of this species has evolved to facilitate exercise at high altitude, we compared the respiratory properties of permeabilized muscle fibers from bar-headed geese and several low-altitude waterfowl species. Respiratory capacities were assessed for maximal ADP stimulation (with single or multiple inputs to the electron transport system) and cytochrome oxidase excess capacity (with an exogenous electron donor) and were generally 20–40% higher in bar-headed geese when creatine was present. When respiration rates were extrapolated to the entire pectoral muscle mass, bar-headed geese had a higher mass-specific aerobic capacity. This may represent a surplus capacity that counteracts the depressive effects of hypoxia on mitochondrial respiration. However, there were no differences in activity for mitochondrial or glycolytic enzymes measured in homogenized muscle. The [ADP] leading to half-maximal stimulation ( | |abstract=Bar-headed geese fly at altitudes of up to 9,000 m on their biannual migration over the Himalayas. To determine whether the flight muscle of this species has evolved to facilitate exercise at high altitude, we compared the respiratory properties of permeabilized muscle fibers from bar-headed geese and several low-altitude waterfowl species. Respiratory capacities were assessed for maximal ADP stimulation (with single or multiple inputs to the electron transport system) and cytochrome oxidase excess capacity (with an exogenous electron donor) and were generally 20–40% higher in bar-headed geese when creatine was present. When respiration rates were extrapolated to the entire pectoral muscle mass, bar-headed geese had a higher mass-specific aerobic capacity. This may represent a surplus capacity that counteracts the depressive effects of hypoxia on mitochondrial respiration. However, there were no differences in activity for mitochondrial or glycolytic enzymes measured in homogenized muscle. The [ADP] leading to half-maximal stimulation (''K''<sub>m</sub>) was approximately twofold higher in bar-headed geese (10 vs. 4–6 µM), and, while creatine reduced ''K''<sub>m</sub> by 30% in this species, it had no effect on ''K''<sub>m</sub> in low-altitude birds. Mitochondrial creatine kinase may therefore contribute to the regulation of oxidative phosphorylation in flight muscle of bar-headed geese, which could promote efficient coupling of ATP supply and demand. However, this was not based on differences in creatine kinase activity in isolated mitochondria or homogenized muscle. The unique differences in bar-headed geese existed without prior exercise or hypoxia exposure and were not a result of phylogenetic history, and may, therefore, be important evolutionary specializations for high-altitude flight. | ||
|keywords=High-altitude adaptation, Hypoxia tolerance, Mitochondrial metabolism, Phylogenetically independent contrasts, Physiological evolution | |keywords=High-altitude adaptation, Hypoxia tolerance, Mitochondrial metabolism, Phylogenetically independent contrasts, Physiological evolution | ||
|mipnetlab=CA Vancouver Richards JG, CA Hamilton Scott GR | |mipnetlab=CA Vancouver Richards JG, CA Hamilton Scott GR | ||
Revision as of 10:51, 26 May 2015
| Scott GR, Richards JG, Milsom WK (2009) Control of respiration in flight muscle from the high-altitude bar-headed goose and low-altitude birds. Am J Physiol Regul Integr Comp Physiol 297:R1066-74. |
Scott GR, Richards JG, Milsom WK (2009) Am J Physiol Regul Integr Comp Physiol
Abstract: Bar-headed geese fly at altitudes of up to 9,000 m on their biannual migration over the Himalayas. To determine whether the flight muscle of this species has evolved to facilitate exercise at high altitude, we compared the respiratory properties of permeabilized muscle fibers from bar-headed geese and several low-altitude waterfowl species. Respiratory capacities were assessed for maximal ADP stimulation (with single or multiple inputs to the electron transport system) and cytochrome oxidase excess capacity (with an exogenous electron donor) and were generally 20–40% higher in bar-headed geese when creatine was present. When respiration rates were extrapolated to the entire pectoral muscle mass, bar-headed geese had a higher mass-specific aerobic capacity. This may represent a surplus capacity that counteracts the depressive effects of hypoxia on mitochondrial respiration. However, there were no differences in activity for mitochondrial or glycolytic enzymes measured in homogenized muscle. The [ADP] leading to half-maximal stimulation (Km) was approximately twofold higher in bar-headed geese (10 vs. 4–6 µM), and, while creatine reduced Km by 30% in this species, it had no effect on Km in low-altitude birds. Mitochondrial creatine kinase may therefore contribute to the regulation of oxidative phosphorylation in flight muscle of bar-headed geese, which could promote efficient coupling of ATP supply and demand. However, this was not based on differences in creatine kinase activity in isolated mitochondria or homogenized muscle. The unique differences in bar-headed geese existed without prior exercise or hypoxia exposure and were not a result of phylogenetic history, and may, therefore, be important evolutionary specializations for high-altitude flight. • Keywords: High-altitude adaptation, Hypoxia tolerance, Mitochondrial metabolism, Phylogenetically independent contrasts, Physiological evolution
• O2k-Network Lab: CA Vancouver Richards JG, CA Hamilton Scott GR
Labels: MiParea: Respiration, Comparative MiP;environmental MiP
Stress:Hypoxia
Tissue;cell: Skeletal muscle Preparation: Permeabilized tissue
Regulation: ADP, Substrate Coupling state: OXPHOS
HRR: Oxygraph-2k
