Journal of Applied Physiology, Vol 50, Issue 3 478-481, Copyright © 1981 by American Physiological Society
Temperature regulation in the dog in helium-oxygen environments
P. M. Stein and H. E. Ederstrom
Helium-oxygen mixtures have been reported to alter thermoregulation in
humans and animals because of convective heat transfer differences between
a helium-oxygen and a nitrogen-oxygen environment. Thermoregulation in
unrestrained dogs was tested in a chamber at temperatures of 23, 33, and 43
degrees C, in air or 80% helium-20% oxygen (HeO). Respirations in air in
these temperatures were 15, 134, and 322 breaths/min, respectively. Heart
rates increased with chamber temperature, averaging 69 at 23, 82 at 33, and
103 beats/min at 43 degrees C. In HeO, responses to increasing temperatures
differed from air. Respiration was 13 at 23, 49 at 33, and 336 breaths/min
at 43 degrees C. Heart rates were 79 at 23, 70 at 33, and 97 at 43 degrees
C. Rectal temperatures rose in both atmospheres at 43 degrees C. Shivering
occurred in dogs in HeO at 23 degrees C but not in air. Results indicated
that the dogs' thermoregulatory responses were markedly different in the
two gas mixtures due to convective heat transfer differences, which were
especially noticeable when responses in HeO at 33 degrees C were compared
to those in air.
