Gnaiger 2013 Abstract Mito2013
|Gnaiger E, Søndergaard H, Munch-Andersen T, Damsgaard R, Hagen C, Díez-Sánchez C, Ara I, Wright-Paradis C, Schrauwen P, Hesselink M, Calbet J, Christiansen M, Helge JW, Saltin B, Boushel R (2013) Conserved mitochondrial coupling efficiency and adaptive substrate control in Inuit and Caucasians: adaptation and acclimatization to the Arctic winter.|
Gnaiger E (2013)
Among all humans, the Polar Inuit of Thule and Qaarnaak in Greenland are the northernmost population, limited to 302 in 1950 and dwindling to 180 in 2004. 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 life style in contrast to the traditional active life style of Inuit hunters. 10 years ago the uncoupling hypothesis was presented for mitochondrial haplogroups of arctic populations suggesting that lower coupling of mitochondrial respiration to ATP production was selected for in favour of higher heat dissipation as an adaptation to cold climates [1,2]. It has been hypothesized that climatic pressures exerted selection for mitochondrial haplogroups in arctic populations as an adaptation to the cold, by increasing heat production through a higher mitochondrial proton leak. We studied muscle mitochondrial function in traditional Inuit hunters from Qaarnaak, Northern Greenland and sedentary Caucasian Danes who engaged in a 42 day ski sojourn across the polar ice caps (80-82o latitude). Small muscle biopsies were obtained from the leg (vastus lateralis) and arm (deltoid) muscles in both Inuit and Danes and mitochondrial function was assessed by high-resolution respirometry [3,4]. OXPHOS capacity in the leg was lower in Inuit compared to Danes consistent with differences in mitochondrial density. Nonetheless, Inuit had a higher OXPHOS capacity with fat substrate in both leg and arm muscles. LEAK respiration was proportionate with OXPHOS such that coupling control was equivalent between groups and across muscles of both arm and leg. After 42 days of skiing Danes demonstrated adaptive substrate control through an increase in fatty acid oxidation towards levels of the Inuit. Biochemical coupling efficiency was preserved across variations in mtDNA, muscle fibre type, uncoupling protein-3 content, muscle OXPHOS capacity, leg and arm muscle, and acclimatization level. This study refutes the hypothesis that uncoupling is higher in skeletal muscle of arctic haplotype populations and reveals that mitochondrial coupling control is tightly conserved across haplotype groups and training status despite large adaptive capacities for substrate oxidation.
Labels: MiParea: Respiration, mt-Biogenesis;mt-density, mtDNA;mt-genetics, Comparative MiP;environmental MiP, Exercise physiology;nutrition;life style
Organism: Human Tissue;cell: Skeletal muscle Preparation: Permeabilized tissue Enzyme: Uncoupling protein Regulation: Coupling efficiency;uncoupling, Flux control Coupling state: LEAK, OXPHOS, ET Pathway: F, N, S, NS HRR: Oxygraph-2k, Theory
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Gnaiger Erich1,2, Søndergaard H3, Munch-Andersen T4, Damsgaard R5, Hagen C4, Díez-Sánchez C5, Ara I3,6, Wright-Paradis C3,7, Schrauwen P8, Hesselink M8, Calbet J3,9, Christiansen M4, Helge JW3,10, Saltin B3, Boushel R3,11
1D. Swarovski Research Lab, Dept. Visceral, Transplant Thoracic Surgery, Medical Univ Innsbruck; 2Oroboros Instruments, Innsbruck, Austria; 3Copenhagen Muscle Research Centre, Denmark; 4National Serum Institute, Copenhagen, Denmark; 5Dept. Biochem. Molec. Cell Biol., Univ. Zaragoza, Spain; 6GENUD Toledo Research Group, Univ. Castilla-La Mancha, Spain; 7Dept. Exercise Sci., Concordia Univ., Montreal, Canada; 8NUTRIM - School Nutrition, Toxicol. Metabolism, Dept. Human Biol., Maastricht Univ. Med. Center, The Netherlands; 9Dept. Physical Education, Univ. Las Palmas, Gran Canaria, Spain; 10X-Lab, Dept. Biomed. Sci., Univ. Copenhagen, Denmark; 11Dept. Biomed. Sci., Heart Circulatory Section, Univ. Copenhagen, Denmark.