Carotid chemoreceptor reflex cardioinhibitory responses: comparison of their modulation by central inspiratory neuronal activity and activity of pulmonary stretch afferents.

The differential nature of the modulation of excitatory inputs from various cardiovascular receptor groups by pulmonary stretch afferents, driven by lung inflation, and the central inspiratory neuronal activity, has been demonstrated. At levels of activity of pulmonary stretch afferents and of central inspiratory drive that almost completely suppress the bradycardia of stimulation of the carotid bodies, the response to stimulation of the arterial baroreceptors and cardiac C fibre endings was reduced by 30-58%. In contrast, the bradycardia evoked by pulmonary C fibre stimulation was not significantly affected by either respiratory mechanism.