milk and egg phospholipids act as protective surfactants against luminal acid in necturus gastric mucosa background our previous studies indicate that milk phospholipids have antiulcer properties in rats and humans possibly by forming a hydrophobic surfactant layer at the epithelial surface in the present study we measured intracellular ph and parameters of membrane resistances in gastric epithelium exposed to luminal acid using a microelectrode techniquemethods chambered isolated necturus maculosus antral mucosa was exposed to ph 23 with or without 2025 min pretreatment with milk or egg phospholipids the ph in surface epithelial cells was measured with doublebarrelled liquid sensor phpdmicroelectrodesresults pretreatment with phospholipids 25005000 micrograms pml significantly p 001 n 14 opposed intracellular acidification phospholipids significantly p 005 n 14 increased the ratio of apical and basal membrane resistances suggesting that they primarily affect the apical cell membrane in contrast there was no significant change in transmucosal resistance suggesting lack of effect on paracellular shunts in the leaky epitheliumconclusions exogenous phospholipids of dietary origin may be used to form a protective layer in the gastric mucosa against irritants