Effect of luminal somatostatin on acid secretion and gastrin release

The mechanisms by which somatostatin inhibits acid secretion when infused into the lumen of the stomach have been examined in 20 healthy subjects. The acid secretory response to distension with 500 ml of neutral water was examined in nine successive 10-min test periods in each subject. Samples of serum and boiled neutral gastric juice were collected and frozen for later immunoassay for gastrin. Somatostatin was added to the distending fluid in a concentration of 600 pg/ml in the middle 3 test periods in 10 test subjects, and placebo added in the same 3 test periods in 10 control subjects. The addition of somatostatin inhibited the rate of acid secretion as compared with placebo alone in the control subjects (p < 0.025) without altering the concentration of immunoreactive gastrin in the serum but reducing the concentration of immunoreactive gastrin in gastric juice (p < 0.02). The data are consistent with the suggestions that the intraluminal administration of somatostatin inhibits antral gastrin release in a paracrinic manner and inhibits acid secretion indirectly by inhibiting lumina gastrin-mediated acid secretory activity.