Phase III of the migrating motor complex: associated with endogenous xenin plasma peaks and induced by exogenous xenin.

Xenin, a recently discovered peptide produced by specific endocrine cells of the duodenal mucosa, has shown exocrine, endocrine and motility effects in the gastroenteropancreatic system in animal experiments. The aim of the present investigation was to study the role of xenin in the regulation of duodenojejunal motility of humans. Twenty-nine healthy volunteers from the hospital staff gave informed consent to participate in this investigation. In 20 volunteers, we determined plasma concentrations of immunoreactive xenin at 15 min intervals over a mean time period of 8 h fasting and recorded the interdigestive motor activity of the duodenojejunum. In a double-blind randomized crossover study on other nine subjects, synthetic xenin in a dose of 4 pmol kg-1 min-1 or placebo was infused for 10 min intravenously in the interdigestive period and postprandially after a liquid meal. Duodenojejunal motility was recorded simultaneously. Predefined interdigestive xenin plasma peaks were found to be significantly associated with the phases III of the migrating motor complex. In the interdigestive period, xenin induced a premature phase III activity in each volunteer; this was followed by a second phase III in five out of nine subjects. In the postprandial state, xenin significantly increased contraction frequency and the percentage of aborally propagated contractions. These findings suggest a role of the peptide hormone xenin in modulating interdigestive and postprandial duodenojejunal motility in humans.