Journal of Applied Physiology, Vol 61, Issue 5 1623-1633, Copyright © 1986 by American Physiological Society
Effects of subanesthetic doses of inert gases on behavioral thermoregulation in mice
R. G. Pertwee, N. R. Marshall and A. G. Macdonald
Mice exposed to subanesthetic partial pressures of N2O (0.25 to 0.75 atm)
or N2 (5.7 or 11.33 atm) and allowed to choose between a warm and a cool
environment showed a marked preference for the cooler environment. This
behavior was associated with the onset of hypothermia, with deep body
temperature falling by up to about 3 degrees C, usually to a new, steady
level. Both the length of time spent in the cooler environment and the
degree of the hypothermia produced increased with the partial pressure of
N2O or N2 used. The effects of N2O on behavioral thermoregulation and body
temperature were reversible. There was a correlation between anesthetic
potency and the ability of both gases to alter thermoregulation, suggesting
that the effect of these agents on thermoregulation was caused by the same
molecular interactions as those which underlie anesthesia. Since both gases
elicited changes in behavioral thermoregulation promoting rather than
opposing the onset of hypothermia, it is concluded that they may have acted
to lower the level at which deep body temperature was being regulated.
