Endocrine Abstracts

Mitochondria oxidize food substrates to generate energy for cellular work and heat is variably generated depending on the degree of coupling of electron transport to oxidative phosphorylation (OXPHOS). It has been hypothesized that climatic pressures exerted selection for mitochondrial haplogroup in arctic populations for a lower coupling of mitochondrial respiration to ATP production in favor of heat production. In this study muscle mitochondrial function was studied in Inuit from northern Greenland and sedentary Caucasian Danes who travelled to Greenland. Muscle biopsies were obtained from the vastus lateralis and deltoid muscles and mitochondrial function was assessed by high-resolution respirometry. OXPHOS capacity in the leg (vastus lateralis) was lower in Inuit compared to Danes (70±4 vs. 90±5 pmol/mg/sec). Leak respiration was proportionate with OXPHOS such that mitochondrial coupling efficiency was equivalent between groups and across muscles of both arm and leg. The traditional Inuit had a higher OXPHOS capacity with lipid substrate compared to Danes (27±3 vs. 22±3 pmol/mg/sec). In conclusion, this study refutes the hypothesis that mitochondrial uncoupling and metabolic heat production is higher in arctic haplotype populations, yet reveals acclimatization of mitochondrial substrate control in arctic inhabitants.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.