ELECTROMYOGRAPHY AND MANOMETRY OF THE PELVIC COLON - A CONTRIBUTION TO THE UNDERSTANDING OF ITS FUNCTION

Objective: 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.Design: Electrical and motor activity was studied in 2 0 men and 20 women during a 2-h fast and for 2 h after a 1000-kcal mea l, and also after a bile salt microenema. Methods: An intraluminal pro be with three sets of two electrodes and one mini-balloon was used for simultaneous EMG and manometry recording. Results: Four types of spik e bursts were observed: (1) migrating long spike bursts that initiated propagating pressure waves on 99% of occasions; (2) non-migrating lon g spike bursts that did not originate pressure waves; (3) rhythmic sho rt 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 lon g 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 t wo peaks. A rectosigmoidal pressure gradient was shown. The bile salt microenema produced a desire to defecate and increased motility in onl y half of the cases. Conclusion: The rectosigmoidal pressure gradient was due to: (1) higher-amplitude pressure waves in the sigmoid colon t han in the other two sites, and (2) propagating relaxation waves in th e rectum and in the rectosigmoid junction.