Neural regulation of gastrin and somatostatin secretion in rat gastric antral mucosa.

A muscle-stripped mucosal sheet obtained from rat antrum was mounted in an Ussing chamber and used to examine the regulation of gastrin and somatostatin secretion by antral neurons. The neurons were activated pharmacologically with 1,1-dimethyl-4-phenylpiperazinium (DMPP) or electrically by field stimulation using aluminum foil electrodes layered over the edge of the mucosal sheet. Field stimulation caused an increase in gastrin and somatostatin secretion that was dependent on the strength of the stimulus (10-30 V). Field stimulation at 30 V, 10 Hz, 4 ms caused a sixfold increase in gastrin and a twofold increase in somatostatin secretion that were nearly abolished by tetrodotoxin (85-89% inhibition). Atropine partially inhibited the gastrin response (34 +/- 6%) but had no effect on the somatostatin response. DMPP caused lesser, though significant, increases in gastrin (166%) and somatostatin (83%) secretion that were nearly abolished by hexamethonium (84-91%) but were not significantly affected by atropine. The increase in somatostatin secretion caused by DMPP and field stimulation, as well as the resistance of gastrin and somatostatin secretion to atropine, was consistent with preferential activation of noncholinergic neurons at the stimulatory modalities used. The pattern and magnitude of gastrin and somatostatin response to pharmacological and electrical stimulation of antral neurons were similar to those previously observed in the vascularly perfused whole rat stomach.