Neurogenic non-adrenergic cutaneous vasodilatation elicited by hypothalamic thermal stimulation in dogs.

Hypothalamic heating in dogs with depleted peripheral adrenergic transmitter stores by means of chronic application of reserpine elicits increase of hindpaw blood flow. The vasodilator response is not affected by alpha- and beta-adrenergic or cholinergic blocking substances, nor by histamine-, or prostaglandin-antagonists. Dopamine and ergometrine produce cutaneous vasoconstriction which is antagonized or prevented by haloperidol. The hypothalamic vasodilator response is abolished after intra-arterial injection of haloperidol, after lumbar sympathetic chain section, or by high doses of hexamethonium. The results indicate neurogenic non-adrenergic control of skin blood flow in thermoregulation possibly acting through inhibition of dopaminergic vasoconstrictor mechanisms.