The effect of environmental temperature on thermoregulatory disturbances caused by hypoxaemic hypoxia in the guinea pig.

Unanaesthetized guinea-pigs, unadapted to cold, were used to study the effect of 20--30 min hypoxaemic hypoxia on the thermoregulatory responses to a moderately low ambient temperature. Hypoxia was produced by intravenous infusion of gaseous CO2. The rate of CO2 administration was adjusted to obtain oxygen uptake equivalent to 70% of the value found at neutral temperature. It was found that at 28 degrees C neither the internal nor the surface temperature changed significantly during hypoxia and oxygen uptake returned to its initial value 15--20 min after cessation of CO2 infusion. At 15 degreesC both the internal and surface temperature as well as oxygen uptake were reduced during hypoxia and they did not return to the initial level 60 min after cessation of CO2 infusion. The temperatures measur-d and oxygen uptake decreased further after each succesive period of CO2 infusion.