Human duodenal motor activity in response to acid and different nutrients.

Duodenal motor activity in response to intraduodenal infusion of small volumes of acid and nutrients of different chemical composition was studied in 10 healthy humans, using a water-perfused catheter incorporating 20 antropyloroduodenal sideholes. Saline and dextrose did not affect motility. Acid very rapidly (in 39 +/- 11 sec) increased the number of pressure waves (P = 0.035) and antegradely propagated pressure waves (P = 0.02). After lipid infusion a considerable lag time (163 +/- 81 sec) was observed, followed by a prominent increase in duodenal pressure waves (P = 0.02) and antegradely propagated pressure waves (P = 0.002). Furthermore, lipid-induced propagated pressure waves traveled over significantly longer distances (4.5 to 6 cm) than those induced by acid infusion (3 cm). We conclude that the motor response to small amounts of intraduodenal nutrients and acid is dependent on the chemical composition of the stimulus. The findings suggest that chemoreceptors in the duodenal wall provide input to local or regional control mechanisms involved in the regulation of duodenal motility.