Hyposensitivity to vasopressin in patients with hepatitis B-related cirrhosis during acute variceal hemorrhage. It has been suggested that vasopressin given during hemorrhage may be less effective than when given during a stable state in a portal-hypertensive rat model. This study was designed to evaluate the hemodynamic response to vasopressin infusion in 25 HBsAg-positive cirrhotic patients. Nine patients had active variceal hemorrhage before vasopressin infusion, and the other 16 patients were in a stable condition at the time of infusion. The two groups of patients were similar in baseline values except that a higher heart rate was found in patients with hemorrhage (96 +/- 20 vs. 73 +/- 10 beats/min, mean +/- S.D., p less than 0.01). Thirty minutes after vasopressin infusion (0.66 units/min), hepatic venous pressure gradient significantly decreased in both bleeding and stable patients (from 21 +/- 9 to 18 +/- 9 mm Hg, p less than 0.05; and from 18 +/- 4 to 8 +/- 3 mm Hg, p less than 0.0001, respectively). However, the decrease of hepatic venous pressure gradient was less obvious in bleeding patients as compared with stable patients (4 +/- 3 vs. 9 +/- 2 mm Hg, p less than 0.0001). A significant reduction of hepatic venous pressure gradient after vasopressin infusion was found in five bleeding patients without shock (from a median of 16 mm Hg [range = 12 to 26] to 11 mm Hg [range = 6 to 18], p less than 0.05), but not in four bleeding patients with shock (from 28 [range = 15 to 36] to 25 [range = 18 to 33] mm Hg, p greater than 0.05). 