Gastrin and somatostatin secretion by perfused rat stomach: functional linkage of antral peptides.

The isolated vascularly perfused rat stomach was used to study the polarity, kinetics, and stoichiometry of gastrin and somatostatin secretion and the interaction of the two antral peptides. The secretion of gastrin (79%) and somatostatin (95%) was predominantly in the circulation. Methacholine (5 x 10(-8) to 5 x 10(-4) M) produced a biphasic dose-dependent increase in gastrin secretion. The maximal gastrin response (434 +/- 89% above basal levels; P less than 0.001) was partially inhibited by 10(-8) M atropine and completely inhibited by 10(-7) M atropine. Methacholine produced a dose-dependent inhibition of somatostatin secretion; the inhibition was blocked by atropine. An inverse relationship between the secretion of gastrin and somatostatin was noted in the basal state and during infusion of methacholine or prostaglandin E2; the latter had effects on gastrin and somatostatin secretion opposite to those of methacholine. The data, together with data reported elsewhere that somatostatin antiserum stimulates gastrin secretion in the perfused stomach, are consistent with the hypothesis that gastric somatostatin secretion exerts a continuous restraint on basal gastrin secretion and that stimulation of gastrin secretion may be mediated in part by inhibition of somatostatin secretion.