Respiratory modulation of afferent terminal excitability in the nucleus tractus solitarius

The excitability of vagal and carotid sinus nerve afferent terminals within the nucleus of the tractus solitarius has been studied in cats and rabbits using the technique of antidromic activation. Although the excitability of superior laryngeal nerve afferent terminals was observed to fluctuate in phase with the central respiratory cycle, no equivalent variations in sinus nerve terminal excitability were observed. Whilst recording from single identified vagal afferents, no respiratory-related changes in the excitability of baroreceptor afferent terminals could be demonstrated, though such modifications in terminal excitability were readily seen in lung stretch afferent terminals.