Figure 2. Average (mean plus/minus SEM) neurocirculatory responses to the administration of fentanyl in awake subjects and to induction of anesthesia with 2.0 mg *symbol* kg sup -1 propofol. After propofol induction, heart rate (HR) increased significantly more in the placebo group when compared to fentanyl-treated groups, (section)P < 0.05. (dagger)P < 0.05 versus fentanyl groups. * P < 0.05 versus respective value at conscious baseline.