Acetylsalicylic acid (ASA) alters the gastric mucosal barrier as measured by the transmucosal potential difference (PD). The effect of the newly developed histamine H2-receptor antagonist 2-(2-(5-dimethylaminoethylfuran-2-ylmethylthio)ethylamino)-5-(6-methylpyrid-3-ylmethyl)pyrimid-4-one trihydrochloride (SKF 93479) on the ASA-induced drop in gastric PD was studied in 6 healthy volunteers. Mean basal PD was -38.5 to -39.5 mV. After 1000 mg of ASA PD decreased in 10-15 min to -25 mV. In subjects pretreated orally with 0.5 mg/kg SKF 93479, PD rose during 30-45 min to -53.5 mV. After ASA PD fell to -38.5 mV, but did not fall below normal.