POSTERIOR PITUITARY EXTRACT is

known to lower the portal venous pres-sure in animalsl-3 and in man a similar effect has been demonstrated during the control of bleeding from esophageal varices with intra-venous pitressin.44 It has been suggested that pitressin lowers portal pressure by increasing splanchnic resistance.7 The present communication concerns the effects of intravenous pitressin on splanchnic hemodynamics in control subjects and in pa-tients with liver disease. The patients in-cluded some with cirrhosis in whom the portal vein was patent and some with a surgical portacaval anastomosis. Patients with normal liver structure but with occlusion of the por-tal vein were also studied. It was thus pos-sible to study the effects of pitressin upon the splanchnic hemodynamics as a whole, and also upon the liver hemodynamics independ-ent of the splanchnic bed in patients in whom portal venous blood was totally diverted from the liver. Methods The patients were divided into three groups. Group 1 consisted of four subjects without liver disease, group 2 consisted of 10 patients with portal cirrhosis in whom splenic venography had confirmed that the portal vein was patent. These patients had varying degrees of portal hyperten-sion. Group 3 consisted of 11 patients with portal cirrhosis and a patent end-to-side portacaval an-astomosis confirmed by splenic venography, and two patients in whom splenic venography showed a blocked portal vein and who had a normal liver biopsy. Estimation of Hepatic Blood Flow A size-9 radiopaque cardiac catheter was intro-duced into one of the main right hepatic veins under fluoroscopic control. The catheter was posi-tioned freely in the central portion of the righ