Response of large hindlimb veins of the dog to sympathetic nerve stimulation

Abstract

In dogs anesthetized with pentobarbital, the venous segment from the lateral saphenous vein at the ankle to the common iliac vein, was perfused at constant flow with autologous arterial blood at 37[degree]C. Inflow and iliac vein pressures were measured. Flow was adjusted to give an initial pressure gradient of 20 or 40 mm Hg. The lumbar sympathetic chain was divided and stimulated maximally at different frequencies. The pressure gradient increased at 0.5 cycle/sec, and further increases were graded to the frequency of stimulation. Larger increases in perfusion gradient were seen when the initial gradient was 40 mm Hg. The time from onset of stimulation to peak response decreased with increasing frequency of stimulation. Analysis of the separate responses of thigh and leg veins showed that the cutaneous portion of the lateral saphenous vein was highly reactive; it became nonreactive abruptly in the popliteal fossa on receiving its first large tributary from muscle. The medial saphenous vein reacted similarly. Adrenergic fibers may be absent in muscle and thigh veins.