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Prostaglandin E‐type receptor subtypes and gastroduodenal bicarbonate secretion in rats
Author(s) -
TAKEUCHI KOJI,
YAGI KOJI,
KITAMURA MOTOHIRO,
KUBOMI MASAFUMI,
TASHIMA KIMIHITO
Publication year - 1998
Publication title -
journal of gastroenterology and hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.214
H-Index - 130
eISSN - 1440-1746
pISSN - 0815-9319
DOI - 10.1046/j.1440-1746.1998.01737.x
Subject(s) - medicine , endocrinology , agonist , duodenum , receptor
We investigated the relationship between prostaglandin E‐type receptor (EP receptor) subtypes and gastroduodenal HCO 3 − secretion in rats. Under urethane anaesthesia, a stomach mounted in an ex vivo chamber or a proximal duodenal loop was perfused with saline and the HCO 3 − secretion was measured at pH 7.0 using a pH‐stat method and by adding 10 mmol/L HCl. Prostaglandin E 2 (PGE 2 , i.v.) increased HCO 3 − secretion in both the stomach and duodenum; this action was verapamil sensitive and only in the duodenum was potentiated by isobutylmethyl xanthine (IBMX). Duodenal HCO 3 − secretion was also stimulated by both sulprostone (EP 1 /EP 3 agonist), enprostil (EP 1 /EP 3 agonist), misoprostol (EP 2 /EP 3 agonist), 11‐deoxy PGE 1 (EP 3 /EP 4 agonist) and ONO‐NT‐012 (EP 3 agonist), but was not affected by either butaprost (EP 2 agonist) or 17‐phenyl‐ω‐trinor‐PGE 2 (EP 1 agonist). In contrast, gastric HCO 3 − secretion was stimulated by sulprostone, enprostil and 17‐phenyl‐ω‐trinor‐PGE 2 , but not by misoprostol, butaprost, 11‐deoxy PGE 1 or ONO‐NT‐012. The EP 1 antagonist SC‐51089 inhibited the HCO 3 − stimulatory action of sulprostone in the stomach but not in the duodenum. Isobutylmethyl xanthine potentiated the HCO 3 − response to sulprostone in the duodenum, while verapamil reduced the response in both the stomach and duodenum. These results suggest that PGE 2 stimulates HCO 3 − secretion via different EP receptor subtypes in the stomach and duodenum: in the former the EP 1 receptors linked to Ca 2+ and in the latter, the EP 3 receptors coupled with both cAMP and Ca 2+ .