Small bowel myoelectric activity in peritonitis.

Peritonitis is associated clinically with paralytic ileus, but the physiologic mechanisms of the effects of peritonitis on bowel myoelectric activity have not been explored. Bipolar electrodes were inserted into the rats, and myoelectric control recordings were obtained for 4 h/d for 5 consecutive days. Peritonitis was then induced, and myoelectric recordings were again obtained. Each animal served as its own control. Prior to induction of peritonitis (control), phase I, II, and III myoelectric activity was present in all recordings. The cycle duration of the migrating myoelectric complex was 17.17 +/- 0.39 minutes, and the migration velocity of phase III was 0.61 +/- 0.02 cm/min. The most striking feature during peritonitis was the complete inhibition of phase II activity. Phase III activity, however, was present with a cycle duration of 16.69 +/- 0.42 minutes. This study shows that some features of intestinal myoelectric activity (phase III) are preserved during episodes of peritonitis, and others are changed (phase I) or lost (phase II). Disappearance of phase II activity in this type of ileus emphasizes its importance in normal small bowel motility.