Subscribe to RSS
DOI: 10.1055/s-2007-1024846
II. Morphological Adaptations of Human Skeletal Muscle to Chronic Hypoxia*
* This work was supported by grant 3.036.084 from Swiss National Science FoundationPublication History
Publication Date:
14 March 2008 (online)
Abstract
Muscle structural changes during typical mountaineering expeditions to the Himalayas were assessed by taking muscle biopsies from 14 mountaineers before and after their sojourn at high altitude (> 5000 m for over 8 weeks). M. vastus lateralis samples were analyzed morphometrically from electron micrographs. A significant reduction (-10%) of muscle cross-sectional area was found on CT scans of the thigh. Morphologically this loss in muscle mass appeared as a decrease in muscle fiber size mainly due to a loss of myofibrillar proteins. A loss of muscle oxidative capacity was also evident, as indicated by a decrease in the volume of muscle mitochondria (-25 %). In contrast, the capillary network was mostly spared from catabolism. It is therefore concluded that oxygen availability to muscle mitochondria after prolonged high-altitude exposure in humans is improved due to an unchanged capillary network, supplying a reduced muscle oxidative capacity.
Key words
high altitude - hypoxia - stereology - mitochondria - myofibrils - computed tomography - capillaries - fiber size