Regional difference in ambient intraluminal gastric acidity after cimetidine monitored by intragastric pH-metry.

Acid secretion was monitored in five duodenal ulcer patients using intragastric glass pH electrodes located in the gastric body and antrum under basal conditions and after the administration of cimetidine. It was shown that differences exist between the body and antral pH in the basal state and in the response to cimetidine. The basal hydrogen ion concentration (mean +/- SEM, mmol/l) in the body, 25.97 +/- 5.03, exceeded that in the antrum, 10.59 +/- 6.44 (p less than 0.05). After cimetidine, the pH rose to 3.5 at both electrodes, this stage being shorter in the antrum (16 min) than body (54 min) (p less than 0.0125). During the next stage the pH rose above 3.5 and the hydrogen ion concentration (mean +/- SEM, mmol/l) was very low in both the body, 0.05 +/- 0.01 (p less than 0.0005 compared to basal) and antrum, 0.08 +/- 0.05 (p less than 0.05 compared to basal). Recovery to basal pH levels occurred more quickly in the body than antrum. Intragastric pH-metry offers a reliable method for studying the mode of action of pharmacological agents on the stomach and contributes information not made available by routine gastric analysis.