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Periodic rectal motor activity: the intrinsic colonic gatekeeper?
1Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, USA.
The American Journal of Gastroenterology
|May 1, 1996
Summary
Periodic rectal motor activity (PRMA) is common in healthy individuals, occurring more frequently at night. This rectal activity appears to be triggered by colonic events and may prevent premature stool passage.
Area of Science:
- Gastroenterology
- Colorectal Physiology
- Digestive System Motility
Background:
- Rectal motor activity patterns are not well understood.
- Characterizing these patterns and their diurnal variations is crucial for understanding normal bowel function.
Purpose of the Study:
- To characterize rectal motor activity patterns.
- To investigate diurnal variations in rectal motor activity.
- To examine relationships between rectal activity, proximal colonic activity, and meals.
Main Methods:
- A 30-hour ambulatory motility study was conducted.
- Pressure activity was recorded at multiple colonic sites in 18 healthy subjects.
Main Results:
- Periodic rectal motor activity (PRMA), characterized by tonic and phasic bursts, was observed in all subjects.
- PRMA occurred more frequently nocturnally, with increased cycle number and duration, and shorter intervals.
- Most PRMA cycles were segmental or retrograde, suggesting a braking function, and were temporally associated with proximal colonic events.
Conclusions:
- PRMA is a normal rectal function, more prevalent at night.
- PRMA is likely triggered by the arrival of stool or gas in the rectum.
- PRMA may act as an intrinsic braking mechanism to prevent premature colonic content expulsion, especially during sleep.