The effects of vasopressin on hepatic haemodynamics in the cirrhotic and non-cirrhotic rat.

Liver blood flow (xenon-133 clearance method) and portal venous flow were measured in cirrhotic and non cirrhotic rats following the infusion of vasopressin at varying rates. At low rates of infusion, vasopressin had no significant effect on portal venous flow or liver blood flow in cirrhotic or non-cirrhotic rats. Infusion of vasopressin at a rate of 0.08 microU/g body wt/min in non-cirrhotic rats and 0.04 and 0.08 microU/g body wt/min in cirrhotic rats decreased portal venous flow and increased liver blood flow. At higher rates of infusion (0.2 microU/g body wt/min in non-cirrhotic rats and 0.16 microU/g body wt/min in cirrhotic rats) these effects were reversed. Furthermore, an infusion of 0.08 microU/g body wt/min vasopressin significantly reduced portal pressure in the cirrhotic rat. However, portal pressure was not significantly altered following an infusion of 0.16 microU/g body wt vasopressin. The implications of these findings in relation to the possible deleterious effects of high rates of vasopressin infusion in the management of portal hypertension and bleeding oesophageal varices is discussed.