Evaluation of effects of ethyl alcohol and bismuth subsalicylate on gastric mucosal barrier in man

The mucus-bicarbonate barrier provides the first line of defense against po tentially harmful gastric luminal contents. Its integrity can be assessed i n man by demonstrating the presence of a pH gradient across the mucus gel l ayer, from the acidified lumen to near-neutral pH at the mucosa. Our aim wa s, firstly, to assess the effects of ethyl alcohol and bismuth subsalicylat e on the integrity of this lumen-to-mucosal pH gradient and, secondly, to e valuate whether pretreatment with bismuth subsalicylate would protect again st any deleterious effects of ethyl alcohol. Ten healthy adults underwent t wo upper endoscopic procedures with microelectrode measurement of juxtamuco sal pH gradients. At the first endoscopy, the effects of 30 mi of bismuth s ubsalicylate on the gradient was evaluated. At the second endoscopy, gradie nts were measured before and after luminal installation of 60 mi of ethyl a lcohol (40% v/v) and following pretreatment with either 30 mi of bismuth su bsalicylate or placebo. pH measurements were technically easy to perform an d provided consistently reproducible results. A distinct juxtamucosal pH gr adient (pH 4.0 +/- 0.2 units) was identified in all subjects in the basal s tate. Neither bismuth subsalicylate nor ethyl alcohol had a significant eff ect on these gradients. We conclude that a distinct pH gradient between gas tric luminal fluid and the mucus gel layer can be readily demonstrated in m an. Neither bismuth subsalicylate nor ethyl alcohol have a significant effe ct on this gradient.