Role of cerebral arterial blood in the regulation of brain temperature in the monkey.

HAYWARD,JAMESN., AND MARY ANN BAKER. Role of cmdral arterial blood in the rqphtion of brain temperature in the monkey. Am. J. Physiol. 215(Z): 389-403. 1.968.-The major determinant of cerebral temperatures in the monkey is the temperature of the arterial blood perfusing the brain. We measured arterial blood temperatures in the aortic arch simultaneously with those at extracranial and intracranial sites in 16 chronic monkeys. Sequential thermal changes occurred in the central arterial blood, cerebral. arterial blood, and in the brain during feeding, sleeping, arousal, and saline injections. Information about the thermal state of the body core is carried rapidly by the arterial blood to the thermodetector neural elements in the preoptic-anterior hypothalamic region of the brain. Maneuvers which after ventilation and the levels of carbon dioxide in the blood c.ln change the tone of the cerebral vessels and cause a shift in cerebral blood flow. In our monkeys such shifts in the rate of AO~V of the cooler arterial blood through the j(varmer brain altered the convective heat transfer in the brain and predictably changed the brain-blood temperature gradients. Our concept of the role of the cerebral arterial blood in homeothermy of the brain in the primate is applicable as a general approach to the study of brain temperature and temperature regulation in other mammals.