[Chemical structure and biological activity of cholecystokizin octapeptides with respect to the stomach and pancreas].

Dose response curves of the octapeptide of cholecystokinin (CCK-8) and 3 of its methoxinine analogues have been established in 4 conscious dogs with respect to gastric and pancreatic secretion. In the analogues the methionine was replaced by methoxinine in position 3 (B) and (D) or 6 (C). Of the 4 tested substances CCK-8 exhibited most activity with regard to pancreatic protein secretion, followed by B, C, and D. Analogue C had the strongest stimulating effect on gastric acid secretion, while its effect on pancreatic secretion was minor. Correlation of chemical structure with biological activity points to the importance of the methionine residue in position 6.