SELECTIVE BRAIN COOLING INCREASES CORTICAL CEREBRAL BLOOD-FLOW IN RATS

To evaluate the effect of selective brain cooling on cortical cerebral blood flow, we reduced brain temperature in nitrous oxide anesthetize d adult rats using a high speed fan while keeping rectal temperature a t 37-38-degrees-C. During selective brain cooling, cortical cerebral b lood flow, as measured by laser-Doppler flowmetry, increased to 215 +/ - 26% (mean +/- SE) of baseline at a cortical brain temperature of 30. 9 +/- 0.5-degrees-C and a rectal temperature of 37.5 +/- 0.1-degrees-C . During rewarming, as brain temperature increased, cortical cerebral blood flow decreased. The cerebral vasodilatory response to hypothermi a may explain its protective effects during and after cerebral ischemi a.