Journal of Applied Physiology, Vol 52, Issue 1 109-113, Copyright © 1982 by American Physiological Society
Rate of uptake of carbon monoxide at different inspired concentrations in humans
H. A. Jones, J. C. Clark, E. E. Davies, R. E. Forster and J. M. Hughes
The rate of uptake of carbon monoxide (CO) in the lungs of normal subjects
were measured at inspired concentrations of less than 1, 300, and 3,000 ppm
(less than 0.0001-0.3%) using radioactive CO (11CO). In nine subjects the
rate of uptake was monitored at the mouth during rebreathing. At inspired
CO concentrations of approximately 1, 300, and 3,000 ppm and a mean
alveolar O2 fraction of 0.15, the mean lung diffusing capacity was 25.8,
26.4, and 25.3 ml . min-1. Torr-1, respectively. In seven subjects the
measurements were repeated after a period of O2 breathing, giving a mean
alveolar O2 fraction of 0.78. The calculated membrane diffusing capacity
was 31.9, 33.7, and 32.0 ml . min-1. Torr-1 at less than 1, 300, and 3,000
ppm inspired CO. We conclude that there is no difference in the rate of
uptake of CO over the range of concentrations studied in these experiments.
No evidence for the presence of a facilitated transport system for CO in
the normal human lung was found.
