This study was designed to investigate the role of bradykinin in the aggravation of acute pancreatitis. After injection of bradykinin 2 micrograms/kg to anesthetized rabbits with cerulein-induced acute pancreatitis, the pancreatic blood flow through gastroduodenal and superior mesenteric arteries (GDAF and SMAF) was determined with electromagnetic blood flow meters, the serum amylase level was measured, and pancreatic tissue was observed histologically. In rabbits treated with a supramaximal dose of cerulein alone (20 micrograms/kg/h), pancreatic blood flow was decreased and the serum amylase level was increased significantly by the early phase, and histological examination showed acute edematous pancreatitis. In rabbits treated with cerulein and bradykinin, GDAF and SMAF were significantly diminished at 300 min (51 +/- 5% and 50 +/- 4%, respectively, p < 0.05), and the serum amylase level rose significantly at 180 and 300 min (730 +/- 130% and 1,190 +/- 200%, respectively, p < 0.01) compared with rabbits treated with cerulein alone, and histological examination revealed pancreatic necrosis and greater inflammatory cell infiltration. These findings suggest that bradykinin has an additive role in the aggravation of acute pancreatitis.