Journal of Applied Physiology, Vol 39, Issue 5 857-859, Copyright © 1975 by American Physiological Society
Luft's syndrome: O2 cost of exercise and chemical control of breathing
N. H. Edelman, T. V. Santiago and H. L. Conn Jr
The oxygen cost of exercise and chemical control of breathing were studied
in a subject with Luft's syndrome, a disorder in which skeletal muscle
mitochondria have a high "resting" O2 consumption which is imcreased only
slightly by stimulation with excess phosphate acceptor, but a normal P/O
ratio. The O2 consumption was more than three times normal (1.05 1/min) at
rest but could be doubled when stimulated by maximal exercise. The O2 cost
of exercise was similar to that of normal subjects. At rest, arterial blood
PCO2 and ventilatory response to CO2 were normal, while ventilatory
response to hypoxia was four times the predicted value. The data 1)
confirm, in vivo, the normal respiratory efficiency of skeletal muscles in
this disorder; 2) suggest that in vitro estimates of the extent to which
mitochondrial respiration can be stimulated may not correlate with in vivo
determinations; and 3) suggests that hypermetabolism per se can cause the
ventilatory adjustments which are associated with exercise in normal
subjects.
