Absence of synchrony between human small intestinal migrating motor complex and rectal motor complex

Both the human small intestine and rectum exhibit motor activity in which relatively brief bursts of powerful regular contractions recur with a similar periodicity. We used prolonged ambulant manometry to test the hypothesis that these activities are synchronous. Pressure activity from the duodenojejunum and the rectum was recorded continuously for 24 h in eight freely ambulant healthy adults. A total of 61 migrating motor complexes and 61 rectal motor complexes occurred in the group; the median periodicities of the two rhythms differed significantly (P = 0.025). There was no evidence of synchrony between the two biorhythms. We conclude that they are independent oscillations.