Control of gastric mucus phospholipid content and composition by cholinergic and adrenergic mediators

1. The secretion of choline-containing phospholipids by gastric mucosal cells in response to neural mediators was investigated using beta-adrenergic and cholinergic agents. 2. A 2.7-fold increase in phospholipid secretion occurred with isoproterenol, while pilocarpine evoked 1.4-fold increase and the effects were inhibited by the respective antagonists. 3. The phospholipid secretory responses were stimulated by dibutyryl-cAMP and phorbol myristate acetate (PMA), but not by 4 alpha-phorbol-12,13-didecanoate which does not activate protein kinase C. The effects of dibutyryl-cAMP and PMA were additive, the the PMA induced phospholipid secretion was inhibited by a protein kinase C inhibitor, tetracaine. 4. The phospholipids secreted in response to isoproterenol showed a 2.1-fold decrease in lysophosphatidylcholine, while those secreted in response to pilocarpine were enriched 2.3-fold in lysophosphatidylcholine, and 1.5-fold in sphingomyelin, and showed 23% lower content of phosphatidylcholine. 5. The results suggest that cholinergic and beta-adrenergic mediators participate in defining the gastric mucus phospholipid content and composition, and hence influence the mucosal protective capability.