[Representation of the pulse wave of blood pressure by the series of impulses of the pulse-rhythmic neurons in the nucleus tractus solitarii].

Baroreceptor afferent fibers from the aortic arch and carotid sinus project to the nucleus of solitary tract in the medulla. The aim of this study was to define the relation between the activity of neurons in this nucleus and changes of the blood pressure in the aorta during the pulse wave. Impulses of 74 pulse-rhythmic neurons, i.e. neurons discharging in bursts of impulses synchronously with the pulse wave, were recorded in acute experiments on 30 rabbits. Impulse histograms triggered by the R wave of the ECG and the averaged pulse wave over 250 consecutive R-R intervals were compared. These post-R histograms showed a close correlation of impulse activity with the pulse wave for most (74%) neurons. The beginning of the burst of impulses corresponded to the beginning of the pulse wave and the highest frequency of discharges coincided with the steepest rise in blood pressure of the pulse wave. The similarity of the histograms to the pulse wave shows that the pulse-rhythmic neurons integrate mostly the afferent input received from the arterial baroreceptors.