title: Muscarinic stimulation of inositol phosphate accumulation and acid secretion in gastric fundic mucosal cells.
abstract: The muscarinic agonist, carbachol (CCh), was shown to stimulate the production of inositol phosphates (IP) in isolated cells from rabbit fundic mucosa. This stimulatory effect was time- and dose-dependent: EC50 values for IP1, IP2 and IP3 accumulation were not statistically different. The mean value was 30 +/- 8 microM (n = 6). The corresponding maximal stimulation (% of basal value) observed after 20 min incubation in the presence of 100 microM CCh was 160 +/- 15%. CCh-induced IP accumulation was abolished by atropine (Ki = 0.32 +/- 0.18 nM (n = 3)). The CCh concentrations leading to half-maximal inhibition of N-[3H]methylscopolamine binding and half-maximal IP accumulation were similar. The half-maximal value for CCh-induced aminopyrine accumulation was 8-times lower. These results indicate that IP3-mediated mobilization of intracellular Ca2+ might be involved in CCh-induced acid secretion by parietal cells.
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology; D002217:Carbachol / Q000378:metabolism / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005744:Gastric Acid / Q000378:metabolism*; D005748:Gastric Fundus; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism; D011817:Rabbits; D011976:Receptors, Muscarinic / Q000187:drug effects*; D013403:Sugar Phosphates / Q000378:metabolism*
chemical_list: D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D011976:Receptors, Muscarinic; D013403:Sugar Phosphates; D002217:Carbachol; D002118:Calcium