Dogs with experimental cirrhosis of the liver but without intrahepatic hypertension do not retain sodium or form ascites.

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Abstract
Dogs with portal cirrhosis but without portal hypertension (end-to-side portacaval anastomosis) retain sodium and expand plasma volume before ascites formation. In our study, dogs were subjected to bile duct ligation and simultaneous side-to-side portacaval anastomosis (PCA) in order to create a canine model of hepatic cirrhosis without intrahepatic or portal hypertension. The effect of normalizing intrahepatic pressures in the face of venous outflow block on sodium handling was studied. 13 dogs survived the surgical procedures and were followed. Two dogs developed sodium retention and ascites at 5-6 wk (livers were cirrhotic) when the PCA spontaneously closed. 11 dogs were free of sodium retention and ascites for as long as 12 wks after surgery, while ingesting 35 meq/d of sodium. In this group glomerular filtration rate remained normal throughout the period of observation and there was no expansion of plasma volume. Nine of these dogs were then fed 85 meq/d of sodium; eight remained in sodium balance and one retained sodium and went on to develop ascites. When 10-15 mg i.m. of desoxycorticosterone acetate (DOCA) was given daily, five dogs developed sodium retention and ascites, while four escaped from DOCA. Dogs who developed ascites had either a partially occluded PCA (4/5) or a patent PCA, but with a significant portacaval pressure gradient of 9.5 cm H2O (1/5). In all four dogs who escaped from DOCA, the PCA was widely patent and the mean pressure gradient was only 1.6 cm H2O. Both groups were equally cirrhotic, as judged by histological and biochemical parameters. We conclude that normalizing intrahepatic pressure by providing an outflow tract for the cirrhotic liver will abolish that component of early renal tubular sodium retention not due to portal venous hypertension or ascites sequestration.