Effect of pentagastrin and caerulein on intragastric pressure in the dog.

When gastric acid was not neutralized, doses of pentagastrin as small as 1 mug kg-1 hr-1 decreased intragastric pressure in dogs. When gastric acid was neutralized the smallest effective dose of pentagastrin was 8 mug kg-1 hr-1 which is 16 times the D50 for acid secretion. Thus the decrease in intragastric pressure by small doses of pentagastrin is mediated at least in part by acid secretion. Even with gastric neutralization, a dose of caerulein as small as 63 ng kg-1 hr-1, which is the D50 for pancreatic protein secretion, decreased intragastric pressure. These findings support the view that inhibition of gastric pressure occurs with physiological doses of the cholecystokinin-like peptide caerulein but only with pharmacological doses of pentagastrin.