Response of capacity and resistance vessels of dog's limb to sympathetic nerve stimulation

Abstract

In a study of the reaction of the capacity vessels of the dog''s hindlimb to sympathetic nerve stimulation, the skeletal muscles were paralyzed, the circulation of the limb arrested, and the venous pressure in the limb monitored. Since changes in activity of the muscles of the pre-capillary vessels had no effect on the venous pressure, changes in venous pressure, after it had stabilized, were due to active alterations in the capacity vessels. Venous responses to a standard stimulus were unaffected by the metabolic changes in the occluded limb. The response of the capacity vessels of the occluded hindlimb to electric stimulation of the lumbar sympathetic chain (15 v, 0.5 m/sec) was compared with that of the resistance vessels perfused at constant flow. The pattern of the stimulus-response curves was identical. There was an increase of smooth muscle tension in both sets of vessels at 0.2 impulses/sec. The tension increased gradually as the frequency of stimulation was increased and approached a maximum between 10 and 20 impulses/sec.