Evidence for H2-receptor-mediated feed-back regulation of histamine release from endocrine cells in the rat stomach.

1. Pentagastrin reduces the concentration of gastric mucosal histamine in the rat. This effect is counteracted by large doses of histamine H2-receptor agonists which are particularly effective if infused I.V. 2. After blockade of histamine H2-receptors but not of H1-receptors, the pentagastrin-induced reduction of mucosal histamine is greatly augmented and H2-receptor agonists no longer inhibit the response to pentagastrin. 3. It is suggested that in the rat stomach, H2-receptors occur on the histamine storing endocrine cells as well as on parietal cells and that mobilized mucosal histamine inhibits further release of histamine by way of H2-receptor-mediated auto feed-back.