Scott 2009 Proc Biol Sci

Scott GR, Egginton S, Richards JG, Milsom WK (2009) Evolution of muscle phenotype for extreme high altitude flight in the bar-headed goose. Proc Biol Sci 276:3645-53.

» PMID: 19640884

Scott GR, Egginton S, Richards JG, Milsom WK (2009) Proc Biol Sci

Abstract: Bar-headed geese migrate over the Himalayas at up to 9000 m elevation, but it is unclear how they sustain the high metabolic rates needed for flight in the severe hypoxia at these altitudes. To better understand the basis for this physiological feat, we compared the flight muscle phenotype of bar-headed geese with that of low altitude birds (barnacle geese, pink-footed geese, greylag geese and mallard ducks). Bar-headed goose muscle had a higher proportion of oxidative fibres. This increased muscle aerobic capacity, because the mitochondrial volume densities of each fibre type were similar between species. However, bar-headed geese had more capillaries per muscle fibre than expected from this increase in aerobic capacity, as well as higher capillary densities and more homogeneous capillary spacing. Their mitochondria were also redistributed towards the subsarcolemma (cell membrane) and adjacent to capillaries. These alterations should improve O₂ diffusion capacity from the blood and reduce intracellular O₂ diffusion distances, respectively. The unique differences in bar-headed geese were much greater than the minor variation between low altitude species and existed without prior exercise or hypoxia exposure, and the correlation of these traits to flight altitude was independent of phylogeny. In contrast, isolated mitochondria had similar respiratory capacities, O₂ kinetics and phosphorylation efficiencies across species. Bar-headed geese have therefore evolved for exercise in hypoxia by enhancing the O₂ supply to flight muscle. • Keywords: Oxygen transport cascade, High altitude adaptation, Physiological evolution, Phylogenetically independent contrasts

• O2k-Network Lab: CA_Vancouver_Richards JG, CA Hamilton Scott GR

Labels: MiParea: Respiration, mt-Biogenesis;mt-density, Comparative MiP;environmental MiP, Exercise physiology;nutrition;life style 

Stress:Hypoxia, Ischemia-reperfusion;preservation"Ischemia-reperfusion;preservation" is not in the list (Cell death, Cryopreservation, Ischemia-reperfusion, Permeability transition, Oxidative stress;RONS, Temperature, Hypoxia, Mitochondrial disease) of allowed values for the "Stress" property. 

Tissue;cell: Skeletal muscle  Preparation: Isolated mitochondria 

Regulation: ADP  Coupling state: OXPHOS 

HRR: Oxygraph-2k