Hormone-stimulated release of pancreatic polypeptide before and after vagotomy in dogs

Abstract

Concentrations of pancreatic polypeptide (PP) in peripheral blood were measured before, during and after infusions of graded doses of synthetic human gastrin I (SHG-I), cholecystokinin 99% pure (CCK-99%), CCK octapeptide (CCK-OP) and pure natural porcine secretin in 6 dogs with gastric and duodenal fistulas. Studies were repeated after truncal vagotomy. Significant increases in concentrations of PP were found with 1 .mu.g.cntdot.kg-1.cntdot.h-1 of SHG-I, 0.25 and 1.0 .mu.g.cntdot.kg-1.cntdot.h-1 of CCK-99%, and 0.06 and 0.25 .mu.g.cntdot.kg-1.cntdot.h-1 of CCK-OP. Significant increases persisted after vagotomy, except at the lower dose of CCK-OP. Postvagotomy responses were significantly less than prevagotomy, except at the higher doses of CCK-99% and CCK-OP. Pure secretin did not change concentrations of PP in blood before or after vagotomy. The most potent stimulant for PP release on a molar basis was CCK-99%, followed by CCK-OP and SHG-I. Cholinergic and humoral agents of the gastrin-cholecystokinin family evidently interact in the normal physiological response of PP to food and that, in dogs, CCK-like peptides are more potent than gastrin.