The effect of the tissue temperature on regional cerebral blood flow (rCBF) was studied using anesthetized and respiratory-controlled normal monkeys. rCBF was sequentially measured by the inhalation hydrogen clearance method, during localized brain heating under generalized hypothermia or differential hypothermia (DH), and was compared to that obtained by whole-body heating and cooling (WB). For WB in 6 animals, the body temperature was controlled by immersion of the body in a hot or cold water bath. rCBF changed with a change in the tissue temperature in the range of 27.8 to 39.7℃,showing a constant 12.2% per degree Celsius change. For DH in 7 animals, the brain was locally heated by external 2450 MHz microwave irradiation, while the body was kept hypothermic (30.0-30.8℃) by immersion in a cold water bath. rCBF rate of 15.2% per degree Celsius change was obtained in response to change in the tissue temperature ranging from 29.4 to 40.7℃. The results indicated that rCBF changed proportionately with the change in the tissue temperature within a specific temperature range between shallow hypothermia and modest hyperthermia.rCBF changed at a higher rate after DH treatment than was possible by WB treatment. The response of the rCBF to changes in the tissue temperature of the normal brain may play a significant role in thermotherapy for brain tumors.
cerebral blood flow
differential hypothermia hyperthermia