Hind-limb vascular responses in anaesthetized dogs to aortic root injections of veratridine.

In dogs anaesthetized with chloralose we determined the reflex responses of the blood vessels in the vascularly isolated hind limb to injection of veratridine into the aortic root. The presence of a cannula tied in the ascending aorta ensured that responses were due to stimulation of nerves only in the region perfused by the coronary arteries. Injections of veratridine resulted in transient decreases in vascular resistance and in venous resistance in a perfused cutaneous vein. The responses were reduced when carotid perfusion pressure was elevated. The afferent pathway for the reflex lay in the vagus nerves and the efferent pathway to the limb was in the sciatic and femoral nerves, but the vasodilatation was shown to be predominantly non-cholinergic.