Spatial and temporal patterns of human jejunal contractions.

We recorded human jejunal motor activity by a 12-lumen manometric tube with recording sites 2 cm apart. The contractile activity in the fasted and the fed state was analyzed by computer to define the spatial and temporal patterns of contractions. Mean duration and area of single contractions during phase III activity were not different from those during phase II activity. By contrast, the frequency and amplitude of contractions, their propagation distance, and the percentage of contractions that propagated for greater than or equal to 2 cm were significantly greater during phase III than during phase II activity. The mean frequency and percentage of propagated contractions in the fed state were intermediate between those during phase II and phase III activity. Mean propagation distance of postprandial contractions was not different from that of phase II contractions. Most contractions in the fed state were uncoordinated at adjacent recording sites. Occasionally, large-amplitude and long-duration contractions, called individual migrating contractions, propagated over long distances and frequently over the entire 22-cm study segment. We conclude that there are some significant differences between the spatial and temporal patterns of contractions between the fed state and phase II and phase III activity. The largely disorganized phasic contractions in the fed state may cause mostly mixing of the ingested meal and its slow distal propagation, whereas the infrequent individual migrating contractions may rapidly propel intestinal contents over longer distances.