Gnaiger 2016 Abstract Mito Xmas Meeting Innsbruck

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The world as a laboratory: exploring mitochondrial fitness.

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Gnaiger E (2016)

Event: Mito Xmas Meeting 2016 Innsbruck AT

A variety of lifestyles developed in human populations to cope with the environmental and socioeconomic conditions in the inhabited areas of our world. Extremes at high altitude and latitude impose stress conditions which require adjustments in physiological performance or limit permanent settlements. Modern strength and endurance training regimes may be closely linked to a variety of traditional life styles. Diversity is nature’s treasure and the subject of comparative physiology [1].

The Polar Inuit of Thule and Qaarnaak in Greenland are among the northernmost populations. This human heritage of a culture and physiological type is endangered not only by a historical politically forced limitation of their territory, but by the current effects of global environmental pollution and climate change, causing social destabilization and a shift towards an unhealthy sedentary in contrast to the traditional active life style of Inuit hunters. The uncoupling hypothesis for mitochondrial haplogroups of arctic populations suggests that lower coupling of mitochondrial respiration to ATP production was selected for in favour of higher heat dissipation as an adaptation to cold climates through a higher mitochondrial proton leak [2]. Our studies show that mitochondrial coupling control in skeletal muscle of Inuit haplogroups is identical to Danes from western Europe haplogroups, such that biochemical coupling efficiency was preserved across variations in muscle fibre type and lifestyle [3].

Unexpectedly, total capacity of oxidative phosphorylation (OXPHOS) in the leg of the Inuit hunters was lower compared to untrained Danes. In line with this apparent ‘mitochondrial paradox’, total OXPHOS capacity decreased in the Danes during 42 days of active skiing on the sea ice in northern Greenland. The Inuit had a higher capacity to oxidize fat substrate in skeletal muscle which increased in Danes approaching the level of the Inuit. A common pattern emerges of mitochondrial acclimatization and evolutionary adaptation in humans at high latitude and high altitude [3-4]: In these environments, economy of locomotion is optimized by preservation of biochemical coupling efficiency at modest mitochondrial density, when VO2max and sustained submaximum performance are not dependent on peripherally increased capacities of oxidative phosphorylation.


O2k-Network Lab: AT Innsbruck Gnaiger E, AT Innsbruck Oroboros, AT Innsbruck MitoFit


Labels: MiParea: Respiration, Comparative MiP;environmental MiP, Exercise physiology;nutrition;life style 


Organism: Human  Tissue;cell: Skeletal muscle 


Regulation: Coupling efficiency;uncoupling  Coupling state: OXPHOS 

HRR: Oxygraph-2k  Event: A1, Oral, Review 


Affiliations and support

Gnaiger E(1,2)
  1. D. Swarovski Research Lab, Dept Visceral, Transplant Thoracic Surgery, Medical Univ Innsbruck
  2. Oroboros Instruments, Innsbruck, Austria

References

  1. Johansen K (1987) The August Krogh Lecture: The world as a laboratory. Physiological insights from nature's experiments. In: Advances in physiological research (McLennan H, Ledsome JR, McIntosh CHS, Jones DR, eds). Plenum Publishing Corporation:377-96
  2. Ruiz-Pesini E et al (2004) Effects of purifying and adaptive selection on regional variation in human mtDNA. Science 303: 223-6.
  3. Gnaiger E et al (2015) Mitochondrial coupling and capacity of oxidative phosphorylation in skeletal muscle of Inuit and caucasians in the arctic winter. Scand J Med Sci Sports 25 (Suppl 4):126–34.
  4. Marconi C, Marzorati M, Cerretelli P (2006) Work capacity of permanent residents of high altitude. High Alt Med Biol 7:105-15.