Fate of intravenously injected trypsin in dog with special reference to the existence of an enteropancreatic circulation.

In 3 mongrel dogs the pancreatic duct and bile duct were cannulated. After intravenous injection of 125I-labelled anionic dog trypsin bile, pancreatic juice and blood samples were collected during 3 h. 125I-trypsin is eliminated from the circulation in dogs with a half time of 15 min. Only 0.15% of the radioactivity is secreted in the pancreatic juice and 0.75% in the bile during 3 h. 10% of the radioactivity in pancreatic juice is protein bound and 45% in the bile is protein bound. The results argue against biologically significant enteropancreatic circulation of trypsin in dogs.