Fig. 3. Representative baroreflex relations for pressor (PE = phenylephrine) and depressor (NP = nitroprusside) responses during control (top ), 1.5 min bupivacaine (BUP, 2 mg/kg;middle ), and 15-min recovery (bottom ). Least-squares linear regression analysis (y = mx + b) was performed on beat-to-beat values of systolic blood pressure and succeeding pulse interval. Thick lines represent the linear fit and broken lines the 95% confidence limits. For all fits, P < 0.0001. Respective fit r values were 0.90767 (control PE), 0.92765 (control NP), 0.81485 (BUP PE), 0.8321 (BUP NP), 0.88337 (recovery PE), and 0.90909 (recovery NP).