Background: In humans, interdigestive acid secretion and antroduodenal motility are closely related with cyclic variations in acid secretion, synchronous with the various phases of the migrating motor complex (MMC). Duodenal acidification inhibits antral motility, but little is known about the effect of acute acid inhibition on antroduodenal motility.
Aim: To study the effect of acute acid inhibition on antroduodenal motility.
Subjects: Ten healthy volunteers (four men and six women: age range 20-31 years).
Methods: Antroduodenal motility (perfusion manometry) and gastric acid secretion (continuous aspiration with recovery marker) were measured simultaneously. Each subject was studied twice in random order during (1) intravenous infusion of saline for one-two complete MMC cycles and (2) during acute acid inhibition with intravenous famotidine (bolus 20 mg, continuous infusion 4 mg/h) for one-two complete MMC cycles or at least 240 min.
Results: In the saline study, acid output in phase III (2.1 +/- 0.3 mmol/10 min) and late phase II (1.7 +/- 0.2 mmol/10 min) was significantly (P<0.05) increased over early phase II and phase I (1.2 +/- 0.2 and 1.2 +/- 0.2 mmol/10 min, respectively). Famotidine increased gastric pH to above pH 6 within 30 min. After acid inhibition, duration of MMC cycle during famotidine (106 +/- 8 min) was not significantly different from the saline experiment (133 +/- 14 min). Phase distribution of the MMC cycle was not significantly different between famotidine (I, II and III: 12 +/- 3, 82 +/- 3 and 5 +/- 1%) and saline (I, II and III: 13 +/- 3, 83 +/- 3 and 4 +/- 1%).
Conclusions: Gastric acid secretion varies cyclically with interdigestive antroduodenal motility. Acute acid inhibition with intravenous famotidine does not significantly affect interdigestive antroduodenal motility.