Murray 2015 Exp Physiol
|Murray AJ (2015) Energy metabolism and the high-altitude environment. Exp Physiol 101:23-7.|
Abstract: At high-altitude barometric pressure falls, challenging oxygen delivery to the tissues. Thus, whilst hypoxia is not the only physiological stress encountered at high-altitude, low arterial PO2 is a sustained feature, even after allowing adequate time for acclimatisation. Cardiac and skeletal muscle energy metabolism is altered in subjects at, or returning from, high-altitude. In the heart, energetic reserve falls, as indicated by lower phosphocreatine-to-ATP ratios. The underlying mechanism is unknown but in the hypoxic rat heart fatty acid oxidation and respiratory capacity are decreased, whilst pyruvate oxidation is also lower after sustained hypoxic exposure. In skeletal muscle, there is not a consensus. With prolonged exposure to extreme high-altitude (> 5500 m) a loss of muscle mitochondrial density is seen, but this was not observed in a simulated ascent of Everest in hypobaric chambers. At more moderate high-altitude, decreased respiratory capacity may occur without changes in mitochondrial volume density, and fat oxidation may be downregulated, though this is not seen in all studies. The underlying mechanisms, including the possible role of hypoxia-signalling pathways, remain to be resolved, particularly in light of confounding factors in the high-altitude environment. In high-altitude adapted Tibetan natives, however, there is evidence of natural selection centred around the hypoxia-inducible factor (HIF) pathway, and metabolic features in this population (e.g. low cardiac PCr/PCr, increased cardiac glucose uptake, lower muscle mitochondrial densities), share similarities with those in acclimatised lowlanders, supporting a possible role for the HIF pathway in the metabolic response of cardiac and skeletal muscle energy metabolism to high-altitude. This article is protected by copyright. All rights reserved.
• O2k-Network Lab: UK Cambridge Murray AJ
Labels: MiParea: Respiration, Comparative MiP;environmental MiP, Exercise physiology;nutrition;life style
Organism: Human Tissue;cell: Heart, Skeletal muscle