Cerebral Cooling During Increased Cerebral Blood Flow in the Monkey. ∗

Abstract

Summary

Temperature measurements were made simultaneously in the arterial blood and in deep brain strctures in 7 chronically prepared rhesus monkeys during both spontaneous ventilation and controlled ventilation. During normal breathing, cerebral temperatures were 0.2-0.5°C higher than the temperature of the arterial blood with identical sites in the right and left cerebral hemispheres showing nearly identical temperatures. During hypercapnia accompanied by increased cerebral blood flow, cerebral temperatures cooled to only 0.1-0.2 °C above the arterial blood. During hypocapnia accompanied by decreased cerebral blood flow, brain-blood temperature gradients were increased above control levels. Intracerebral temperature gradients are basically dependent upon the rate of removal of heat from the brain by the arterial blood.