INHIBITORY CHOLINERGIC EFFECTS OF ESAPRAZOLE ON GASTRIC-SECRETION AND PLASMA GASTRIN-LEVELS IN THE DOG

The effects of esaprazole, a novel antiulcer drug, on gastric acid secretion and plasma gastrin levels were investigated in dogs provided with a gastric fistula or Heidenhain pouch. Esaprazole affected in a different extent the tests performed on dogs with a gastric fistula. The greatest inhibitory effect was obtained against 2-deoxy-D-glucose-induced acid output and gastrin release. An intermediate inhibition by esaprazole was detected on bethanechol-evoked secretion, and the lowest activity was found versus histamine-stimulated secretion. All these responses were strongly inhibited by the antimuscarinic drug pirenzepine used as reference drug. Moreover, both esaprazole and pirenzepine prevented the acid secretory response to a test meal in dogs with a Heidenhain pouch, without significantly affecting plasma gastrin levels. The present results suggest that the depressant action of esaprazole on gastric secretion depends on its peripheral anticholinergic activity, consisting of a partial blockade of acid output and a main reduction of vagally mediated gastrin release. On the basis of these findings, the antiulcer activity of esaprazole might be in part ascribed to its inhibitory effects on gastric secretion.