Ion transport and electrical resistance of the gastric mucosa are responsible for the generation of the transmucosal potential difference (PD), which is considered an index of mucosal integrity. 2. The aim of the present work was to study the effect of some antisecretory and gastroprotective agents on PD in stomachs damaged by ethanol. 3. Control PD values measured in anesthetized rats were 35 to 40 mV (mucosa negative). Oral administration of 96% ethanol or intragastric instillation of 20% ethanol induced an abrupt fall in PD from the basal values of 40.4+/-1.0 mV and 39.6+/-0.1 mV to 14.6+/-2.5 mV and 11.7+/-1.3 mV, respectively. 4. Oral and/or topical pretreatment with the antisecretory agents ranitidine and timoprazole, as well as with the gastroprotective agents PGE2 and pentacaine, but not with an aluminum- and magnesium-containing antacid and with sucralfate, reduced the maximal drop of PD caused by ethanol. 5. After the administration of concentrated ethanol, hemorrhagic lesions were formed in the glandular stomach. 6. With the exception of ranitidine, all the drugs tested prevented the development of lesions after ethanol administration. 7. The results indicate that the gastric barrier can be protected by various drugs that act through different mechanisms.
