Nature of aortic smooth muscle responses to changes in venous return in intact dogs

Abstract

A response of the aortic smooth muscle to reduction in venous return was demonstrated previously. The present experiments were performed to determine whether these responses were of a reflex origin rather than being attributable to viscoelastic mechanisms. Viscoelastic mechanisms could not account for changes seen in the aortic pressure diameter relationship curve. On the other hand, it was demonstrated that the response was abolished by eliminating sympathetic input to the aorta via spinal cord transection. This and other evidence demonstrate beyond doubt that the aortic response to reduction in venous return is of neurogenic origin and constitutes a well-integrated reflex. However, experimental evidence is presented which clearly indicates that the receptors for the aortic smooth muscle response are not located in either the carotid sinus or aortic arch but must be located elsewhere in the system.

Smooth muscle relaxation and local hydraulic impedance properties of the aorta

“…Inflation of a balloon in the IVC was used to construct aortic area-pressure relationships over a wide range of pressures. Nicolosi and Pieper (23,24) have shown that acute reductions in venous return affect aortic pressure-diameter relationships via reflex changes in sympathetic input to the aorta. The effects on aortic pressure-diameter relationships in their study were measured at 30-45 s after the reduction in venous return.…”

In Vivo Measurement of Regional Large Artery Compliance by Intravascular Ultrasound Under Pentobarbital Anesthesia

“…3,4,13More recent work using external ultrasound in an in vitro model has demonstrated changes in vascular compliance due to smooth muscle injury; however, neural factors are absent in such a preparation. 14 In vivo studies have demonstrated changes in large artery compliance in response to neural stimulation9>15 as well as to pharmacologic agents,?, 10,16,17 However, these studies used externall5 or intralumina116,1~ dimension gauges or surgically implanted ultrasonic dimension crystals, 7,9,10 which may alter the vascular response to neural or pharmacologic agents and assume a circular shape to calculate luminal area.…”