Acid releases motilin from human duodenum in vitro

The effect of hydrochloric acid and sodium hydroxide on motilin release from human duodenal mucosa was studied in vitro. Tissue was incubated in 2 ml chambers continuously perfused with medium and was exposed repeatedly to the stimuli. Motilin released into the medium was determined by a specific radioimmunoassay. Whereas alkalinisation abolished basal motilin release, acidification resulted in a 14-fold increase of peptide secretion. The results indicate that motilin secretion can be stimulated in vitro and that the perfusion system described may be a useful tool in studying the mechanism of gastrointestinal hormone release.