Separation of Responses of Arteries and Veins to Sympathetic Stimulation

Abstract

Lumbar sympathetic nerve stimulation produced an increase in arterial, small vessel and venous segmental resistances in the perfused hind paw of the dog. Repeating the stimulation, after having sectioned the somatic nerve bundles accompanying the main arterial supply of the paw, brought about an increase only in venous resistance which was equal to or greater than that obtained in the control period. This venous constrictor response was reduced greatly by the intravenous administration of adrenergic neuronal blocking drugs, by local infiltration of procaine around the paw, or by transection of the subcutaneous tissue around the paw and the nerves accompanying the veins. These results indicated that sympathetic postganglionic fibers supplying the arteries and small vessels were derived from nerve bundles accompanying the arteries (tibial and deep fibular nerves). The fibers supplying the veins are distributed more diffusely in that they are found in somatic nerve bundles accompanying the veins themselves, in the tibial nerve, and in the subcutaneous tissue of the paw.