Reflex renal vasoconstriction on portal vein distension.

Abstract

The present experiments were designed to study effects of neural control mechanisms on renal sympathetic nerve activity during acute portal vein distension in anesthetized dogs. Following the inflation of a balloon placed into the main portal vein of animals with the neuraxis intact (intact group), portal vein pressure at a site of the splanchnic regions increased significantly. Mean blood pressure (MBP) fell significantly and then renal vascular resistance (RVR) increased significantly in parallel with changes in portal venous pressure. In animals with sinoaortic denervation (SAD group), changes in portal venous pressure during the inflation of a balloon did not differ from the intact group. However, decreases in MBP in the SAD group were greater than that in the intact group, and sinoaortic denervation did not alter increases in RVR. In animals with both sinoaortic denervation and cervical vagotomy (vagotomy group), portal vein distension produced more profound hypotension, and significant increases in RVR occurred. This increase in RVR, however, was abolished by renal nerve denervation. The results of the present study indicate that increases in RVR during the portal vein distension, which is associated with systemic hypotension, may be mediated by an activation of efferent sympathetic renal nerves and modified by at least two neural reflex mechanisms such as carotid sinus baroreceptors and cardiopulmonary baroreceptors. In addition, local reflex systems such as stretch receptors in the venous wall of the portal vein may be involved in excitatory response to renal sympathetic nerve, leading to renal vasoconstriction, during the portal vein distension.

Role of Volume Redistribution in the Congestion of Heart Failure

“…Local reflex systems such as stretch receptors in the venous wall of the portal vein function as a link between the splanchnic compartment and the kidneys. This local reflex may be involved in an excitatory response to the renal sympathetic nerves, leading to renal vasoconstriction during the portal vein distension (hepatorenal reflex) . The interaction between liver/spleen and kidneys is complex and implies the presence of osmo‐, chemo‐, and baroreceptors in the liver that sense specific stimuli and react to them through neural‐mediated circuits that directly affect the kidneys and their function .…”

“…This local reflex may be involved in an excitatory response to the renal sympathetic nerves, leading to renal vasoconstriction during the portal vein distension (hepatorenal reflex). 59 The interaction between liver/spleen and kidneys is complex and implies the presence of osmo-, chemo-, and baroreceptors in the liver that sense specific stimuli and react to them through neural-mediated circuits that directly affect the kidneys and their function. 60,61 Receptor activation results in an increase of sympathetic nervous tone and sodium and water absorption through the kidney.…”

Mechanical Properties of Smooth Muscle Portal Vein in Normal and Dystrophin‐Deficient (MDX) Mice

“…Although this study is the first to report data concerning the physiology of the portal vein in normal mouse, the motor control mechanisms of this blood vessel have been extensively studied in other species, both in vitro (see survey by Ljung, 1970) and in vivo (Groszmann et al 1982;Koyama et al 1986). The results of the present investigation show that the spontaneous motor activity of the mouse portal vein is similar to that observed in other animals, indicating that this smooth muscle has a number of properties in common with visceral smooth muscle of the single-unit type (Roddie, 1962;Mollie et al 1968;Johansson & Mellander, 1975;Fig.…”

Metabolic syndrome and the hepatorenal reflex

“…[910218241263] However, studies in both humans and animals have documented an immediate decrease in renal blood flow, glomerular filtration rate, and urine flow, as well as increased sodium retention in response to increased intrahepatic pressure or reduced liver blood flow due to the reflex activation of rSNA. [244498103112127129130160]…”