Effect of duodenal ulcerogens cysteamine, mepirizole, and MPTP on duodenal myoelectric activity in rats.

Increased gastric acid secretion, enhanced acid delivery to the duodenum, and reduced alkaline secretion in the proximal duodenum are relatively well-established pathophysiologic abnormalities in duodenal ulcer. Impaired duodenal motility, however, may also contribute to duodenal ulceration by altering the distribution of acid and alkaline secretions along the upper digestive tract. We tested the hypothesis that the duodenal ulcerogens cysteamine, MPTP, and mepirizole modify duodenal motility in the rat and that motility changes might be a common and early alteration in experimental duodenal ulceration. All three duodenal ulcerogens rapidly produced extensive changes in duodenal myoelectric activity and reduced the frequency of myoelectric slow waves. Cysteamine induced marked hypermotility for at least 6 hr; MPTP rapidly decreased motility and fragmented the myoelectric migrating pattern. Mepirizole induced biphasic changes: an early hypermotility phase of about 30 min was followed by profound hypomotility. These results indicate that marked alterations of duodenal motility are common during experimental duodenal ulceration. In light of the differential effect of the ulcerogens on duodenal motility, it remains to be determined how these changes influence acid neutralization in the proximal duodenum. Nevertheless, our results suggest that all three duodenal ulcerogens, which are different in structure, alter duodenal motility.