Interaction between the Fastigial Pressor Response and the Baroreceptor Reflex

Abstract

Abstract Experiments were performed on chloralosed cats with recording of blood pressure, heart rate and regional blood flows. The response pattern elicited by stimulation of the cerebellar fastigial nuclei, was closely similar to that caused by carotid baroreceptor unloading. Thus, the cardio‐acceleration caused by fastigial stimulation was due not only to increased accelerans tone, as has been suggested, but also to withdrawal of vagal inhibitory activity. However, electrolytic destruction of the fastigial “pressor area” did not alter the reflex cardiovascular responses to carotid baroreceptor unloading or to somatic pressor afferent stimulation, indicating that this area did not exert any tonic influence on the centres conveying such reflexes. Evidence is presented for a differentiated interaction between the baroreceptor inhibitory reflex and the fastigial excitatory response with a relatively stronger fastigial suppression of the reflex action on the heart than on the vascular bed. This differentiation involves an element of central suppression of the reflex cardiac control, though it is partly a consequence of the different neuroeffector characteristics of heart and vessels.