Pancreatic secretory proteins in sera from rats before and after induction of experimental pancreatitis.

This study has traced the behavior of rat anionic trypsin-like immunoreactivity and pancreatic secretory trypsin inhibitor (PSTI) immunoreactivity in the serum of rats undergoing bile-pancreatic duct infusions of buffered solutions with and without the addition of the bile salt taurocholate. Enzymatic analysis of alpha-amylase was also done. A mild pancreatic inflammation followed infusion of buffer alone, as determined by gross inspection of the pancreas and the behavior of serum levels of the above proteins. Animals infused with buffer and 4% taurocholate had major inflammatory changes, including gross hemorrhage into the gland, and marked elevations in serum levels of the three proteins studied. Graphic analysis of the serum levels revealed distinct sharp rises in the serum levels of all three proteins in the taurocholate group. In the buffered saline group only an initial sharp rise was present, followed by a prolonged decrease back towards base-line values. The immunoreactive trypsin in the taurocholate group was present in three fractions with different molecular weights: trypsin in complex with protease inhibitors, trypsinogen, and trypsinogen, and degradation products. PSTI immunoreactivity showed the molecular size of free inhibitor and that of degradation products. The presence of trypsin in complex with protease inhibitors indicates the formation of active trypsin during acute pancreatitis, which is further supported by the presence of degradation products of trypsin and PSTI.