Regular and irregular cycles of interdigestive contractions in the stomach

Abstract

We have previously reported that during the interdigestive state repeated episodes of high-amplitude contractions interrupted by long-lasting motor quiescence were seen to occur regularly until the next meal in the dog. However, none of the dogs used in our laboratory showed such regular changes in gastric motor pattern all the time during the interdigestive state. In the present study, we measured plasma motilin concentrations and intraduodenal pH together with gastric motor activity in conscious dogs. It was found that as long as intraduodenal pH remained between 7.0 and 8.5 the regular occurrence of the interdigestive contractions was closely associated with increases in the plasma immunoreactive motilin (IRM) concentration. However, when intraduodenal pH became acid, there were no typical interdigestive contractions even though plasma IRM concentration was elevated. We consider that high-amplitude contractions like the interdigestive contractions could not be evoked in the acid-secreting stomach even if the plasma IRM concentration was elevated during the interdigestive state. Acid secretion during the fasted state, the cause of which is not known, seems to be one of the main factors in disturbing the regularity of the interdigestive motor pattern.

Underlying mechanism of the cyclic migrating motor complex inSuncus murinus: a change in gastrointestinal pH is the key regulator

“…Itoh et al. () found that in dogs, fasting irregular contractions are associated with lower duodenal pH and there is a dramatic increase to alkaline pH during strong regular contractions. An almost identical observation was reported in a human study, which found that duodenal pH fluctuates from 2 to 7.5 during the onset of phase II, whereas the pH remains alkaline from late phase II to phase III contractions (Woodtli and Owyang ).…”

Effect of trimebutine maleate on bethanechol-induced contractions of gastrointestinal tract in conscious and anaesthetized dogs.

“…infusion of TM-906 produced a transient suppression of the anomalous, continuous low-amplitude contractions oc curring randomly observed in some of the fasting dogs. The anomalous motor activity in the fasted state is considered to be caused partly by an increase in spontaneous secretion of acid in the stomach (7). The depressive effect of TM-906 on the contractions of the stomach induced by a strong secretagogue (bethanechol) might be related to suppression of the spontaneous increase in acid-secretion.…”

“…Itch et al (7) postulated that one of the main factors disturbing the regularity of fasting motor activity was acid-secretion. In the present experiment, the contractile response to an acid-secreting cholinergic agent, bethanechol (8), and the effect of TM-906 on it were studied in conscious dogs and, in part, anaesthetized dogs with chroni cally implanted force transducers.…”

Interdigestive migrating motor complex -its mechanism and clinical importance

“…5-HT 3 antagonists, which inhibit gastric phase III, have no effects on intestinal phase III (30, 31). When we carefully check MMC recordings in dogs, it is obvious that duodenal phase II/ III is frequently antecedent to gastric phase II/ III (1, 36,37,38,39). However, no reasonable explanation has been shown.…”