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# BRS Physiology - (2) distention of the stomach - (3) vagal stimulation, mediated by gastrin-releasing peptide (GRP) Atropine does not block vagally mediated gastrin secretion because the mediator of the vagal effect is GRP, not acetylcholine (ACh). ## Inhibition of gastrin secretion - H+ in the...

# BRS Physiology - (2) distention of the stomach - (3) vagal stimulation, mediated by gastrin-releasing peptide (GRP) Atropine does not block vagally mediated gastrin secretion because the mediator of the vagal effect is GRP, not acetylcholine (ACh). ## Inhibition of gastrin secretion - H+ in the lumen of the stomach inhibits gastrin release. This negative feedback control ensures that gastrin secretion is inhibited if the stomach contents are sufficiently acidic - Somatostatin inhibits gastrin release. ## Zollinger-Ellison syndrome (gastrinoma) - Occurs when gastrin is secreted by non-β-cell tumors of the pancreas.