Hemodynamic effects of blood volume restitution following a hemorrhage in rats with portal hypertension due to cirrhosis of the liver: Influence of the extent of portal-systemic shunting

Open Access
Publisher Website
Google Scholar
Abstract
The present study investigated whether, in rats with portal hypertension due to cirrhosis of the liver induced by carbon tetrachloride, blood volume restitution following a hemorrhage produces an increase of portal pressure beyond control values, as observed in rats with prehepatic portal hypertension. Since carbon tetrachloride-induced cirrhosis caused mild portal-systemic shunting, in some of the cirrhotic rats (12 of 29 rats) portal-systemic shunting was enhanced by a transient (4 days) partial constriction of the portal vein, which was removed 1 week prior to the study. After baseline measurements of portal pressure and arterial pressure, 15 ml per kg of blood were withdrawn at a rate of 0.3 ml per min and reinfused 15 min later. After blood reinfusion, portal pressure and arterial pressure were measured again, and cardiac output, regional blood flows and portal-systemic shunting were determined using radioactive microspheres. Portal-systemic shunting was 78 ± 11% of total blood flow in the cirrhotic rats that had temporary portal vein constriction, but only 5 ± 2% (p < 0.001) in those that did not. Blood volume restitution in low-portal-systemic shunting rats did not produce any significant modification in splanchnic or systemic hemodynamics. However, in rats with high portal-systemic shunting, blood volume restitution produced a significant increase in portal pressure (from 9.9 ± 0.9 to 13.5 ± 0.9 mmHg, p < 0.02). This increase in portal pressure after blood reinfusion was due to a significant increase in portal vascular resistance (from 1.3 ± 0.2 to 1.9 ± 0.2 mmHg per ml per min per 100 gm, p < 0.05), since no significant changes were observed in either portal blood flow or systemic hemodynamics. Our results show that blood volume restitution after a hemorrhage worsens the portal hypertension syndrome in cirrhotic rats with high portal-systemic shunting but not in those with low portal-systemic shunting, thus demonstrating that the extent of portal-systemic shunting is an important mediator of this deleterious effect.
Keywords