Pancreatic lysosomal thiol proteinases and inhibitors in acute pancreatitis induced in rats.

When examining the level of esterolysis and that of cathepsin B or H, a significant positive correlation was found in the rat pancreas with inflammation induced by a closed duodenal loop, whereas there was a significant negative correlation between the activity of cathepsin B or H and that of its endogenous inhibitors. The levels of endogenous inhibitors of cathepsins B and H in rats with a pancreatitis were lower than in the sham-treated group. The endogenous inhibitors of cathepsins B and H were destroyed by incubation with the supernatant fraction obtained from the inflamed pancreas. These observations indicate that the activities of pancreatic cathepsins B and H are closely related to the severity of acute pancreatitis and that lesser levels of thiol proteinase inhibitors in the pancreatitis group than in the sham-treated group are due to destruction of the inhibitors by the enhanced protease activity.