The function of intrasplenic transplanted hepatocytes in acute liver failure was studied in an experimental model using rat (Lewis syngeneic rat). Acute ischemic liver failure was induced by occlusion of the proximal portal vein and hepatic artery immediately following extracorporeal porto-femoral venous bypass. Rats in group I were untreated and served as control (n = 6). Rats in group II received an intrasplenic transplant of hepatocytes (4 x 10(7) cells) 2 days before liver ischemia (n = 6). Rats in group III received an intrasplenic injection of the equal quantitative liver homogenate instead of hepatocytes 2 days before liver ischemia (n = 6). Serum ammonia and blood glucose were measured before, 1 hour and 2 hour after ischemia. The survival times of animals were evaluated. Serum ammonia was remarkably increased after ischemia in group I (1 hr = 937, 2 hr = 1220 micrograms/dl). On the other hand, in group II, the elevation of serum ammonia was significantly suppressed, less than half of that in group I (1 hr = 425, 2 hr = 463 micrograms/dl). That in group III was similar to group I. Blood glucose was remarkably decreased in all groups, but it was statistically higher in group II (1 hr = 48, 2 hr = 28 mg/dl) than in others (group I 1 hr = 23, 2 hr = 2, group III 1 hr = 29, 2 hr = 10 mg/dl). The mean survival time in group II (191 minutes) was two times longer than those in another two groups.