Topical 16,16-dimethyl-prostaglandin E₂

Abstract

Using a canine chambered stomach preparation, the effects of topical 16,16-dimethyl-prostaglandin E₂ (dmPGE₂) on gastric mucosal morphology, H⁺ loss and HCO₃ ⁻ secretion were assessed. Compared to control studies in which acid alone (100 mM HCl) bathed the epithelium, dmPGE₂ (1 or 4 μg/ml), when applied to gastric mucosa in acid medium, significantly (P<0.01) enhanced H⁺ loss from the bathing solution in a dose-related fashion. These effects, however, were independent of any injury to the epithelium as confirmed by both light and electron microscopy. In other studies in which dmPGE₂ was applied to gastric mucosa in neutral solution (150 mM NaCl, pH 7.0) using identical doses, a dose-related increase (P<0.01) in HCO₃ ⁻ secretion was observed. When the net HCO₃ ⁻ output (μEq/15 min) for each dose of dmPGE₂ employed was compared with the net H⁺ loss (μEq/15 min) for each dose of PG used, no differences were noted. The correlation between H⁺ loss and HCO₃ ⁻ secretion was highly significant (r=0.87;P<0.01). We conclude that with the doses studied, dmPGE₂ is not damaging to gastric mucosa and that the apparent increase in H⁺ loss elicited by dmPGE₂ in acid medium is due to acid neutralization secondary to HCO₃ ⁻ secretion.