PERMEABILITY EFFECTS OF THE E2-PROSTAGLANDINS ON CANINE GASTRIC-MUCOSA

The effects on gastric mucosal permeability (GMP) of the topical application and intravenous administration of prostaglandin E2 (PGE2), 15(S)-15-methyl prostaglandin E2 (15M) and 16,16-dimethyl prostaglandin E2 (16DM) were measured in canine Heidenhain pouches. Two groups of four dogs were used and each experiment consisted of a 3-h perfusion with an acid saline solution containing polyethylene glycol as a volume marker. The prostaglandin was either added to the perfusate or given by constant intravenous infusion. The H+ and Na+ fluxes were used to assess GMP. Topical (1-10 μg/mL) and intravenous (0.3-1.2 μg kg-1 h-1) 16DM increased the apparent Na+ flux into the pouch in association with the secretion of fluid by the pouches, but did not alter H+ flux. The PGE2 applied topically (10-1000 μg/mL) had a similar effect, but intravenously (0.3-1.2 mg kg-1h-1) reduced the volume of pouch secretion and the apparent Na+ flux into the pouch without altering H+ flux. The 15M given in the same concentration as 16DM was without a consistent effect on ionic flux or volume of secretion. The E2 prostaglandins have no effect on normal GMP.