Central summation of barosensory impulses over both carotid sinus nerves in the dog

Stimulation of both CSN in dogs with continuous stimuli decreased blood pressure and heart rate as effectively as intermittent bursts of stimuli. The temporal separation between the stimulus bursts to the two CSN was without effect on the reflex response. Similarly perfusion of both carotid sinuses with pressure pulses which were in phase was no more effective in eliciting the reflex than perfusion with pressure pulses 180 degree out of phase. These results suggest that the barosensory fibers project centrally to independent neuronal pools. Pulsatile perfusion of the carotid sinuses lowered systemic pressure more than nonpulsatile pressure at the same mean level. The greater efficacy of pulsatile pressure appears to result from baroreceptor recruitment and not from the impulse pattern.