Figure 3. Predicted responses to carbon dioxide of the middle cerebral blood flow velocities under the two experimental conditions.

The slopes of the fitted lines in all subjects were significantly different and the response was significantly enhanced in the left middle cerebral artery as compared to the right. (P<0.001, left and right upper panels). The responses of the cerebral circulation to increasing CO₂ levels during skin hypoxia and skin normoxia were significantly enhanced on the left compared to the right (P<0.001, left and right lower panels). Additionally, both were significant compared to the baseline (P<0.001).