The Effect of Somatostatin on Pentagastrin-stimulated Gastric Secretion and on Plasma Gastrin in Man

Three experiments were carried out in each of 6 healthy students on separate days, in a randomized order. Intravenous saline infusions were given for one hour basally in each experiment. During the second hour either pentagastrin, pentagastrin and somatostatin, or somatostatin alone were given. Gastric juice was collected continuously during all experiments. Somatostatin decreased the volume of gastric secretion and the concentrations of acid and pepsin, and output of acid, pepsin, and intrinsic factor (IF). The plasma gastrin concentration was not changed by somatostatin. A rebound effect was seen on pepsin and IF outputs after cessation of somatostatin, and on blood sugar concentration. The present study suggests that somatostatin acts on gastric secretion either directly or by mechanisms other than by inhibition of gastrin. The rebound of pepsin and IF indicates a release-inhibiting action on these substances similar to the effect of somatostatin on the release of some hormones.