Baroreceptor influence on postural changes in blood pressure and carotid blood flow

16 dogs under morphine and Nembutal anesthesia

Denervation of the carotid sinus and aortic arch baroreceptors, and administration of a dihydrogenated ergot alkaloid mixture (Hydergine), followed by 30° head-down and head-up tilting

Control state (intact baroreceptors, no Hydergine) undergoing the same 30° head-down and head-up tilting

Changes in mean systemic blood pressure, carotid blood flow, and heart ratesurrogate