Relationship between interdigestive duodenal motility and fluid transport in humans

In 22 healthy volunteers distal duodenal fluid absorption was related to the interdigestive motility cycle. Fluid absorption was measured with a triple-lumen perfusion technique, and motility was registered with a low-compliance pneumohydraulic system. Pancreatic and biliary secretions were estimated by measurement of bilirubin and amylase release into the duodenal segment. Duodenal fluid absorption rate changed during the interdigestive motility cycle; the highest absorption rate was registered during phase I (low-motor activity) and absorption rate then decreased in parallel with increasing motor activity during phase II (r = -0.69, P less than 0.001). In late phase II a net fluid secretion was frequently registered, together with an increased release of bilirubin into the duodenal lumen. This pattern was seen during perfusion with both glucose-containing (30 mM) and glucose-free solutions. The results show that duodenal fluid absorption rate changes markedly during the interdigestive motility cycle. This effect may be a hydrodnamic phenomenon or may be due to activation of a neural secretory mechanism during phase II.