Changing and Constant Temperatures of the Rat as Thermoregulatory Stimuli

¹ From the Department of Physiology, The Jefferson Medical College of Philadelphia, Philadelphia, Pennsylvania

The separate roles of falling, and constant low, body temperature in stimulating the vasomotor and thermogenetic responses of the white rat have been assessed. Peripheral vasoconstriction (indicated by conductance measurements) was induced by constant low body temperature, the degree being a function of the level of temperature. At any temperature, the degree was further increased initially when the temperature began to fall unless heat production was elevated instead. It was decreased initially when the temperature began to rise. Heat production was not significantly correlated with constant body temperature unless ‘corrected’ to normal temperature according to the Q₁₀ law. Heat production was always significantly increased when an already low temperature was caused to decrease further. Oscillations of colon temperature in animals exposed to constant environments have been described.