Comparative effects of bombesin and porcine gastrin-releasing peptide in the dog.

Bombesin and porcine gastrin-releasing peptide (GRP) share a common C-terminal decapeptide fragment and are known to have similar bioactivity. The potencies of parenterally administered GRP and bombesin have been compared in their effects on gastric acid output, serum gastrin, and serum pancreatic polypeptide. In the dose range 0-720 pmol/kg/hr, infusions of both peptides resulted in dose-related increases of gastric acid output and corresponding elevations of serum gastrin and pancreatic polypeptide. At the dose of 1440 pmol/kg/hr, both bombesin and GRP resulted in a decrease in gastric acid output and serum gastrin. The mechanism of this inhibition is unknown. No significant difference in potency between the two peptides in changing gastric acid output, serum gastrin, and pancreatic polypeptide was observed. The demonstration of equimolar potency of porcine GRP and bombesin support the concept that GRP is mammalian bombesin.