Effect of cimetidine on gastric potential difference in man.

The effect of the histamine H-2 receptor antagonist cimetidine on gastric potential difference (P.D.) has been studied in five healthy volunteers. P.D. was recorded continuously, and basal P.D. (mean +/- S.E.) was -48+/- 1-0 mV. Cimetidine, 300 mg orally, increased P.D. to -64+/- 2-4 mV. Cimetidine also significantly decreased basal acidity from pH 2 to pH 7 within an hour. The effect on both P.D. and pH persisted throughout each 3h study. P.D. has been shown to correlate with changes in the human gastric mucosal barrier. Cimetidine, therefore, may have a protective effect on the gastric mucosal barrier in addition to its suppression of acid secretion.