Variability of skin temperature in the waking monkey.

Temperatures of the brain, skin, and nasal mucosa were recorded along with the cortical electroencephalogram (EEG) in chaired, conscious pigtail monkeys at 25 degrees C air temperature. In undisturbed animals, skin temperatures ranged from 34 to 37 degrees C. When the animal was alerted by visual or auditory stimuli, temperatures on the extremities, tail, nose, ears, and nasal mucosa dropped rapidly to 22-29 degrees C. Temperatures on the proximal limbs and trunk and most of the head remained steady at all times. Average hypothalamic temperature was 0.91 degrees C higher when the extremities, tail, nose, ears, and nasal mucosa were cool than when they were warm, the brain temperature change beginning 80-120 s after the change in peripheral temperatures. A slight decrease in EEG frequency, but no change in amplitude, occurred during skin warming. Anesthetic doses of barbiturate led to a rapid rise in temperature of the extremities, tail, nose, ears, and nasal mucosa and a drop in brain temperature. These large changes in skin temperature in conscious monkeys reflect changes in cutaneous blood flow, the resulting alteration in heat loss leading to a rapid change in deep body temperature. The experiments demonstrate the importance of the state of arousal on autonomic nervous control of peripheral vasomotor tone in the monkey.