Ambient thermal conditions and thermoregulatory mechanisms in fever in rabbits.

At ambient temperatures 10 degrees C, 20 degrees C, 30 degrees C, and 40 degrees C the influence of heat dissipation on the thermoregulatory mechanisms in rabbits with fever was investigated. Temperature of the brain (TBr-accuracy +/- 0.05 degree C) temperature of the nasal mucosa (TN) and temperature of the ear pinna (TAU-accuracy +/- 0.5 degree C) were measured in freely moving rabbits. Changes of conditions of heat dissipation were produced by: preventing heat dissipation by convection and radiation by putting ear-pads on the ear pinnae, high humidity of air for blocking of heat loss through evaporation, and facilitation of heat dissipation through shearing of the fur. The changes of the ambient thermal conditions as well as of the ability of heat dissipation were followed by changes in the dynamics of functions of the remaining (effective) thermoregulatory mechanisms in the rabbits. Thus despite changed thermal conditions of the environment, the TBr of the rabbits with fever was stabilized at a similar level.