Regulatory role of carotid nerve afferences upon the frequency and pattern of spontaneous gasp complexes.

Spontaneous gasps were recorded in pentobarbitone-anesthetized adult cats. Mean interval between gasps in 11 cats with their buffer nerves intact was of 65 sec; it was significantly prolonged to 174 sec after unilateral carotid neurotomy and to 403 sec after bilateral carotid neurotomy. Additional sectioning of both aortic nerves in two cats led to a further increase of intervals between gasps. Inhibition of chemosensory activity during dopamine infusions also reduced the frequency of gasps. Recording of chemosensory impulses from one carotid nerve after unilateral carotid neurotomy, showed reduced discharge frequency or silencing immediately after the augmented inspiration. This effect probably mediated the reduced amplitude of the following series of ventilatory cycles. It is suggested that the peripheral chemosensory in flow adjusts the gain of the vagal inspiration-augmenting reflex.