Electromyography and manometry of the pelvic colon--a contribution to the understanding of its function

To study the adaptation of the rectum to pressure waves in the sigmoid and the motility response to the administration of a bile salt microenema.

Electrical and motor activity was studied in 20 men and 20 women during a 2-h fast and for 2 h after a 1000-kcal meal, and also after a bile salt microenema.

An intraluminal probe with three sets of two electrodes and one miniballoon was used for simultaneous EMG and manometry recording.

Four types of spike bursts were observed: (1) migrating long spike bursts that initiated propagating pressure waves on 99% of occasions; (2) non-migrating long spike bursts that did not originate pressure waves; (3) rhythmic short spike bursts that were also not related to pressure waves; and (4) rhythmic long spike bursts that originated rhythmic segmental pressure waves frequently brought up by a migrating long spike burst. The meal significantly increased the duration of activity of the migrating long spike bursts in the sigmoid colon (from 16.8% before the meal to 21.8% after it, P < 0.05) and the motility index, P < 0.05, both of them in two peaks. A rectosigmoidal pressure gradient was shown. The bile salt microenema produced a desire to defecate and increased motility in only half of the cases.

The rectosigmoidal pressure gradient was due to: (1) higher-amplitude pressure waves in the sigmoid colon than in the other two sites, and (2) propagating relaxation waves in the rectum and in the rectosigmoid junction.