Bradykinin antagonism in ischemia and reperfusion of the pancreas

INTRODUCTION: Acute pancreatitis is characterized by two different courses of the disease, edematous and hemorrhagic-necrotizing pancreatitis. The pathogenesis and causes for the progression of pancreatitis are unknown. Ischemia/reperfusion with formation of oxygen free radicals, activation of leukocytes and consecutive failure of the microcirculation has gained attention as a causative factor. Furthermore, the degree of microcirculatory injury correlates with the severity of pancreatitis. The aim of the study was to investigate the influence of long term reperfusion after ischemia of the pancreas for 2 hours on morphological changes and enzyme release of the pancreas in rats. Since the characteristic features of postischemic pancreatic reperfusion injury are kinin-mediated we employed the bradykinin B2-receptor antagonist HOE 140 to inhibit the progression of postischemic changes of the pancreas. METHODS: Under ether anesthesia Sprague-Dawley rats (n = 28) were laparotomized, the 4 supplying arteries of the pancreas were isolated (gastroduodenal artery, left gastric artery, splenic artery and caudal pancreaticoduodenal artery) and occluded with microvascular clips for 2 hours. At the end of ischemia the abdomen was closed and the animals were allowed to awake. 15 minutes before end of ischemia an osmotic minipump filled with NaCl (ischemia group NaCl), phosphate buffer (ischemia group phosphate buffer) or HOE 140 dissolved in phosphate buffer (ischemia group HOE 140) was placed intraperitoneally. Control animals underwent sham operation without vessel occlusion; the osmotic minipump was filled with 0.9 % NaCl. Five days after ischemia the animals were sacrificed for histology. Amylase concentration and peripheral leukocyte count were determined at baseline and daily after operation. RESULTS: After ischemia of 2 hours during reperfusion of 5 days all 14 animals developed histopathological changes as seen in hemorrhagic-necrotizing pancreatitis with a mortality rate of 50 %. These morphological changes were associated with a significant increase (p < 0.05) of pancreas amylase concentration from 1850 +/- 149 U/L before ischemia to a maximum of 3934 +/- 435 U/L at 1st postoperative day and decreased to 1518 +/- 399 U/L at 4th postoperative day. Leukocyte count increased significantly (p < 0.05) from 10 x 10(12)/L to 31 x 10(12)/L. In control animals as well as in animals receiving HOE 140, morphological and enzyme changes typical for acute pancreatitis were absent, leukocyte count increased only slightly. CONCLUSION: Ischemia of the pancreas of 2 hours with ensuing reperfusion of 5 days induces morphological and biochemical changes as observed in hemorrhagic-necrotizing pancreatitis. Organ dysfunction after ischemia/ reperfusion can be effectively inhibited by administration of the bradykinin-antagonist HOE 140.