Fig. 4. Effect of bupivacaine on the vagal and aortic depressor nerve evoked bradycardia. (A ) Electrical stimulation (8 V × 1 ms, 20 Hz, 2 s) of the distal end of the cut right vagus in the neck evoked a reproducible bradycardia. The application of bupivacaine (3 μg/ml) was associated with a pressor, bradycardic response. However the bradycardia evoked by vagal stimulation was unaffected at the same time the baroreflex gain was reduced by 78%. (B ) Electrical stimulation of the aortic depressor nerve (10 V × 1 ms, 25 Hz for 1 s) evoked a reproducible bradycardia. The systemic application of bupivacaine (3 μg/ml) attenuated the aortic depressor nerve evoked bradycardia and reduced the baroreflex gain by 44%. Both the baroreflex and the evoked aortic depressor nerve bradycardia recovered to control after 5 min of washing.