Effect of acetylsalicylic acid on the amphibian gastric mucosa. I. Electrophysiological and permeability changes.

The effects of acetylsalicylic acid on the in vitro bullfrog gastric mucosa were defined. After mucosal exposure of 10 or 20 mM acetylsalicylic acid, a characteristic series of changes evolved. The potential difference and resistance rose initially. After 15 to 30 min the potential difference declined to zero. Transmucosal resistance remained elevated considerably longer but began to decline toward zero after 30 to 60 min of exposure. Mucosal permeability to mannitol increased as transmucosal resistance declined, but was not markedly elevated until the 2nd hr of exposure to acetylsalicylic acid. The initial rise of potential difference was associated with inhibition of H+ secretion whereas the later decline of potential difference was due to inhibition of Cl- transport. The abolition of short circuit current could not be attributed to mucosal to serosal flux of acetylsalicylate.