Pancreatic secretory activity of secretin5–27 and substituted analogues

Abstract

The effect of secretin5–27 and four substituted analogues (9-Gln-secretin5–27, 15-Asn-secretin5–27, 9-Gln-15-Asn-secretin5–27, and 15-Lys-secretin5–27) on pancreatic secretion in the rat and guinea pig was examined. Secretin5–27 retained significant pancreatic secretory activity in both species. Its efficacy (intrinsic activity) relative to secretin was much higher in the rat (0.2) than in the guinea pig (0.03). The activity of secretin5–27 was not affected by a single or dual substitution of carboxylic acid residues by the corresponding carboxamides or by lysine despite a substantial decrease in the helical character of the peptide.