ENHANCEMENT OF GASTRIC MUCUS PHOSPHOLIPID SECRETION BY AN ANTIULCER AGENT, EBROTIDINE

1. Rat gastric mucosal cells, subjected to phospholipid labeling by in cubating the cell suspension in DR?EM with [H-3]choline, were exposed to different concentrations (0-150 mu M) of H-2-receptor antagonists, ebrotidine and ranitidine, and the phospholipid secretory responses we re evaluated. 2. In the absence of the drugs, the secretion of choline -containing phospholipids over a I hr period averaged 3.97% of the tot al cellular labeled phospholipids. Ebrotidine caused a dose-dependent increase in the rate of phospholipid secretion which was most pronounc ed at 1 hr and persisted for at least 2 hr. The maximal effect was att ained at 120 mu M ebrotidine giving a 36% increase in phospholipid sec retion. 3. The phospholipid secretory response to ebrotidine was accom panied by an increase in gastric mucosal cell cAMP level which reached a maximum value of 2.1-fold over that of controls at 1 hr. Ranitidine , in contrast, neither evoked increase in cAMP level nor caused any st imulation in phospholipid secretion. 4. The results indicate that the gastroprotective properties of ebrotidine are associated with the abil ity of the drug to elicit a rapid stimulation in gastric mucus phospho lipid secretion, and that ranitidine does not possess such property.