Temporal dynamics of the partial pressure of brain tissue oxygen during functional forepaw stimulation in rats

The partial pressure of tissue oxygen (pO(2)) was measured in rat somatosen sory cortex during periodic electrical forepaw stimulation of either 1 min or 4 s in duration, and correlated with simultaneous laser Doppler flowmetr y. For both stimulus durations, a transient decrease in tissue pO(2) preced ed blood flow changes, followed by a peak in blood flow and an overshoot in tissue pO(2) With protracted stimulation, tissue pO(2) remained only sligh tly above pre-stimulus baseline, while blood flow was maintained at a reduc ed plateau phase. A sustained post-stimulus undershoot in tissue pO(2) was observed only for the 1 min stimulus. These findings suggest a complex dyna mic relationship between oxygen utilization and blood flow. (C) 2001 Elsevi er Science Ireland Ltd. All rights reserved.