title: Stimulation of alkaline secretion in amphibian-isolated gastric mucosa by 16,16-dimethyl PGE2 and PGF2 alpha. A proposed explanation for some of the cytoprotective actions of prostaglandins.
abstract: The mechanism of the gastric cytoprotective action of prostaglandins is unknown but seems to be unrelated to inhibition of acid secretion. In the present study, effects of the prostaglandins, 16,16-dimethyl E2 and F2 alpha on H+ and HCO-3 secretion and electrical properties in amphibian-isolated gastric mucosa were studied. Spontaneous net secretion in fundic mucosa from Rana temporaria and Necturus was acid, whereas Necturus antrum secreted only HCO-3. The histamine H2-receptor antagonist, metiamide (10(-3) M), was used to inhibit acid secretion for studies on fundic alkalinization. Nutrient side administration of 16,16-dimethyl E2 (10(-6) M) for 60 min inhibited H+ secretion and stimulated HCO-3 secretion in Rana temporaria fundus. The drug (10(-5) M) also stimulated antral alkalinization. There was a dose-related increase in HCO-3 secretion in Necturus fundus after administration of F2 alpha (10(-5)-10(-4) M), but this drug had no significant effect on H+ secretion. Inhibition of acid secretion by 16,16-dimethyl E2 was associated with an increase in potential difference (PD), but there was no change in electrical resistance. Neither of the prostaglandins affected PD or resistance in alkaline-secreting tissues. Previous work has suggested that gastric HCO-3 secretion has a physiologic role in protecting the mucosal surface. The ability of prostaglandins to stimulate alkaline secretion may contribute to the cytoprotective action of these drugs in the stomach.
mesh_terms: D000818:Animals; D001001:Anura; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity / Q000187:drug effects; D005745:Gastric Acidity Determination; D005750:Gastric Juice / Q000032:analysis / Q000378:metabolism*; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D008785:Metiamide / Q000494:pharmacology; D011459:Prostaglandins E, Synthetic / Q000494:pharmacology*; D011460:Prostaglandins F / Q000494:pharmacology*; D011896:Rana temporaria; D013268:Stimulation, Chemical; D014562:Caudata
chemical_list: D011459:Prostaglandins E, Synthetic; D011460:Prostaglandins F; D008785:Metiamide