Prevention of experimental acute pancreatitis by intraduodenal trypsin inhibitor in rat.

To confirm that trypsin activity is a most important initiating factor in closed duodenal loop pancreatitis in rats, we observed the course of acute pancreatitis when trypsinogen activation was inhibited by intraduodenal infusion of a potent synthetic trypsin inhibitor (TI, nafamostat mesilate) but the other conditions were left unchanged. Intraduodenal and intrapancreatic trypsinogen activation was inhibited for 16 hr after the intraduodenal infusion of the inhibitor, although elevation of serum amylase and immunoreactive trypsin and pancreatic trypsinogen remained similar both in the TI and control groups. The mortality decreased from 44% (control) to 4% (TI) at 48 hr after establishing the model. Active trypsin in duodenal reflux is an initiating factor for further development of acute pancreatitis in the closed loop model, and inhibition of the initial activation of trypsinogen has a favorable effect on acute pancreatitis even if other deleterious factors remain unchanged.