Continuous recording ofpH in the duodenal bulb after food and alkali1

Only recently have we been satisfied with the data obtained from recording the pH of luminal contents within the duodenal bulb in situ. The improvement in technique consisted of concurrent recording of antral and duodenal transmucosal potential differences so that the site of the electrode could be determined without fluoroscopy (Archambault, Rovelstad, and Carlson, 1967). A logical application of this technique was the study of the effects of food and antacids on the acidity of duodenal bulb contents, since some investigators (Fordtran and Collyns, 1966) have found antacids to be more effective after a meal. The use of an indwelling glass electrode has many advantages. It avoids the possibility of the aspirating tubes being obstructed by food particles. Also, tube aspiration from the small volume of the duodenal bulb almost certainly attracts fluids from adjacent sites. The electrode in situ more likely records a pH that represents the fluid bathing the usual ulcer located in the duodenal bulb.