Neural control of vasomotion in rabbit ear is impaired during desynchronized sleep.

In a warm environment the skin vessels of the rabbit ear, dilated during synchronized sleep (SS), reduce their caliber during desynchronized sleep (DS). In a cold environment the ear skin vessels, constricted during SS, increase their caliber during DS. These vascular changes contrast with thermoregulatory homeostasis. They can be accounted for by the decrease in both local transmural pressure and sympathetic vasoconstrictor discharge accompanying the DS phase. A decrease in local transmural pressure prevails in a warm environment and a decrease in sympathetic discharge in a cold environment. Accordingly, the vessel caliber decreases in the heat and increases in the cold. The results of the sympathetic denervation of the ear and of the alpha-receptor blockade confirm the passive nature of vascular changes in the rabbit ear during DS.