MILK AND EGG PHOSPHOLIPIDS ACT AS PROTECTIVE SURFACTANTS AGAINST LUMINAL ACID IN NECTURUS GASTRIC-MUCOSA

Background: Our previous studies indicate that milk phospholipids have anti-ulcer properties in rats and humans, possibly by forming a hydro phobic surfactant layer at the epithelial surface. In the present stud y we measured intracellular pH and parameters of membrane resistances in gastric epithelium exposed to luminal acid using a microelectrode t echnique. Methods: Chambered isolated Necturus maculosus antral mucosa was exposed to pH 2.3, with or without 20-25 min pre-treatment with m ilk or egg phospholipids. The pH in surface epithelial cells was measu red with double-barrelled liquid sensor pH/PD-microelectrodes. Results : Pre-treatment with phospholipids (2500-5000 mu g P/mL) significantly (P < 0.01, n = 14) opposed intracellular acidification, Phospholipids significantly (P < 0.05, n = 14) increased the ratio of apical and ba sal membrane resistances, suggesting that they primarily affect the ap ical cell membrane, In contrast, there was no significant change in tr ansmucosal resistance suggesting lack of effect on paracellular shunts in the 'leaky' epithelium. Conclusions: Exogenous phospholipids of di etary origin may be used to form a protective layer in the gastric muc osa against irritants.