Enhanced cardiac metabolism of plasma glucose in high altitude
natives: a metabolic defense adaptation against chronic hypoxia.
Holden, J. E., C. K. Stone, C. M. Clark, W. D. Brown, R. J. Nickles,
C. Stanley, and P. W. Hochachka.
Departments of Medical Physics, Radiology and Medicine, University
of Wisconsin-Madison, Madison, Wisconsin; Departments of Zoology and
Psychiatry, and Sports Medicine Division, University of British
Columbia, Vancouver, Canada
APStracts 2:0145A, 1995.
The metabolism of glucose in mammalian heart is 25-50% more oxygen
efficient than the metabolism of free fatty acids. To assess the role
of substrate preference in adaptations to chronic hypoxia, positron
emission tomographic measurements of heart regional glucose uptake
rates following an overnight fast were made in volunteer Quechua
subjects and in Sherpa subjects, both indigenous to altitudes of over
3000 m, and in a group of lowlander volunteers. Highest uptake rates
were found in the Quechuas on arrival and in the Sherpas after a
three week period at low altitude, intermediate rates in Quechuas
after a three week period at low altitude and in the lowlanders, and
lowest rates in Sherpas on arrival. These low values were probably
related to the stress of travel to the site of the experiments.
Measured plasma catecholamines, hormones, and substrates indicated
that glucose concentrations correlated best with observed variations
in glucose uptake, with a negative correlation for the control
subjects and a positive correlation for the Quechuas and Sherpas.
Uptake values in Quechuas declined significantly after a three week
period at low altitude, but the positive correlation with glucose
levels persisted. We conclude that an elevated glucose preference in
heart is a true metabolic adaptation in humans adapted over
generations to chronic hypoxia.
Received 8 August 1994; accepted in final form 21 February 1995.
APS Manuscript Number A823-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 April 1995.