Changes in elasticity of pulmonary reflexogenic area with sympathetic activity

Abstract

The isolated rabbit sympathetic nerve-pulmonary artery preparation has been shown to be taken from a part of the pulmonary artery which contains a high concentration of adventitial sensory endings resembling those in the carotid sinus and aortic depressor area. Using this preparation the static bulk modulus of elasticity has been measured under a variety of circumstances. Sympathetic nerve stimulation, increased potassium ion concentration, and l-norepinephrine addition decreased the unstretched circumference of the artery, with increasing strain, increased and then decreased the elastic modulus of the arterial wall, and decreased the change in elastic modulus for any proportionate increase in circumference. Sodium nitrite had opposite actions. Angiotensin and pH changes between 7.0 and 8.1 had no effect on these measurements. A possible cause for some of the divergent conclusions found in the literature, and the relation of these experimental findings to the afferent activity of associated pressoreceptors is discussed.