Inhibitory effect of aprotinin on gastric acid secretion.

Aprotinin was found to inhibit the amplitude of electrically stimulated contractions of the isolated guinea pig ileum with an ID50 of 6.75 X 10(-6) M. Aprotinin inhibited pentagastrin-stimulated gastric acid secretion in the rat, cat, and pig after oral or intraventricular administration. No inhibition of gastric acid secretion was seen after intravenous infusion of aprotinin. When segments of antrum, duodenum, and ileum were incubated in vitro with increasing concentrations of aprotinin, increasing amounts of somatostatin were released from the organs. It is suggested that aprotinin's effects, which are similar to those of somatostatin, may be due to a local release of somatostatin from the D-cells in the gastrointestinal tract.