Inhibition of Gastric Acid Secretion in Man by Peptide Analogues of Cholecystokinin

Abstract

In human subjects gastric acid secretion was stimulated by intravenous infusion of 1 μg of pentagastrin per kilogram hour. One hour after the start of pentagastrin, when acid secretion had reached a plateau, either caerulein (eight tests), a decapeptide extracted from frog skins, or carboxy-terminal heptapeptide amide of cholecystokinin (five tests), each in a dose of 0.1 μg per kilogram hour, was added to the pentagastrin infusion for one hour. Both peptides produced about 70 per cent inhibition of acid output. Since both peptides have the same carboxy-terminal tetrapeptide amide sequence as pentagastrin, presumably they inhibited by competing with pentagastrin for a common receptor. In separate tests this dose of caerulein alone produced slight stimulation of acid secretion in two of five subjects. Screening of related peptides might yield a specific competitive inhibitor of gastrin with even less stimulatory action than was noted with those tested.