Some characteristics of core temperature signals in the conscious goat

In three conscious goats, head and trunk temperatures were altered independently of each other by means of extracorporeal carotid heat exchangers and intravascular heat exchangers in the trunk veins. In 35 experiments heat production and heat loss were measured while head temperature was varied between 35.4 and 42.2 degrees C and trunk temperature between 34.5 and 42.4 degrees C. The largest temperature difference between head and trunk amounted to 6.6 degrees C. Head and trunk generated approximately equal fractions of the total core temperature input to the controller. The distribution of combinations of head and trunk temperatures resulting in constant levels of heat production and heat loss was consistent with the hypothesis that the total core temperature input to the controller equaled the sum of two identical inputs, both rising exponentially with temperature. The hypothesis implies that the input generated by core sensors of temperature in head and trunk is a continuum and conforms with the temperature-response curve of warm receptors.