Wistar rats were implanted with an electrode around the left ADN and a catheter into a femoral artery. The systolic, diastolic and mean arterial pressure and heart rate were recorded in subjects randomly assigned to continuous or intermittent electrical stimulation. The time-course of cardiovascular responses in conscious rats was examined during longer-term (60 min) continuous (n = 6) or intermittent (5 s ON/3 s OFF; n = 10) electrical stimulation (0.5 mA; 0.25 ms; 30 Hz) of the ADN.
The prompt (20 s) hypotensive response was greater under continuous stimulation, but no difference was detected in the bradycardic response. The hypotensive response was sustained only by continuous stimulation while no sustained bradycardia was observed in either protocol.
These findings indicate that continuous stimulation of the ADN is more effective in reducing arterial pressure over a longer period (60 min) of stimulation. Nevertheless, both protocols - continuous or intermittent - were unable to elicit a sustained bradycardia.