A new round in the discussion on the action of secretin on pancreatic protein secretion: a further study on the effect of secretin on pancreatic secretion in dogs.

Whether or not secretin stimulates pancreatic protein secretion is a controversial question. In this investigation, dose-response studies with different secretin preparations were performed in dogs with two different types of pancreatic fistulae. Pure natural secretin (Karolinska Institute, Stockholm), synthetic secretin (Hoechst, Frankfurt), synthetic secretin (Hoechst, Frankfurt), synthetic D-Ala17-secretin (Roche, Basel), and natural secretin (Kabi, Munich) were tested in dogs equipped with a Thomas cannula for collection of pure pancreatic juice. The synthetic secretin was also tested in dogs with a modified Herrera fistula. Potency of the pure natural and the unmodified synthetic secretins was similar. Whereas protein output was significantly stimulated by these secretin preparations, protein concentrations fell to approximately 10 mg ml-1 with incremental doses of infused secretin. The high protein concentrations of 60 up to 120 mg ml-1 found in pure basal pancreatic secretion, suggest that pancreatic protein output may have been a "washout" phenomenon, and that the increasing protein output values were due to rising volume flow of pancreatic juice which is not completely protein-free. Impure secretin preparations and indirect collection techniques also lead to an elevation of pancreatic protein output.