Sensorial and intestinointestinal reflex pathways in the human jejunum

Using an intestinal barostat that maintains a constant pressure within an air-filled bag (12 cm long), the authors have previously shown reflex changes in intestinal tone induced by distention. The aim of this study was to investigate the sensitivity and the responsiveness to such reflexes along the jejunum. Eight healthy volunteers were studied using two barostats operating simultaneously in the proximal and the distal jejunum (located 10 cm and 52 cm caudad to the ligament of Treitz, respectively). With one barostat, standardized distentions (1 minute duration at 10-minute intervals in 4-mm Hg increments) were produced; with the other barostat, intestinal tone was measured as volumetric variations at constant pressure. Perception was scored (0-6) by a questionnaire. The proximal jejunum relaxed in response to distention of the distal jejunum (mean +/- SE, 40% + 7% delta vol; 5.1 + 0.1 perception score at the threshold for discomfort; P less than 0.05 for both). In contrast, the distal jejunum did not respond to distention of the proximal jejunum, whereas the perception scores were similar (10% +/- 5% delta vol; 5.1 +/- 0.1 perception score). Thus, the responsiveness of the proximal jejunum to intestinointestinal reflexes fades distally, whereas intestinal sensitivity to distention remains uniform.