Study of termination of postprandial gastric contractions in humans, dogs and Suncus murinus: role of motilin- and ghrelin-induced strong contraction.

AIM: Stomach contractions show two types of specific patterns in many species, that is migrating motor contraction (MMC) and postprandial contractions (PPCs), in the fasting and fed states respectively. We found gastric PPCs terminated with migrating strong contractions in humans, dogs and suncus. In this study, we reveal the detailed characteristics and physiological implications of these strong contractions of PPC. METHODS: Human, suncus and canine gastric contractions were recorded with a motility-monitoring ingestible capsule and a strain-gauge force transducer. The response of motilin and ghrelin and its receptor antagonist on the contractions were studied by using free-moving suncus. RESULTS: Strong gastric contractions were observed at the end of a PPC in human, dog and suncus models, and we tentatively designated this contraction to be a postprandial giant contraction (PPGC). In the suncus, the PPGC showed the same property as those of a phase III contraction of MMC (PIII-MMC) in the duration, motility index and response to motilin or ghrelin antagonist administration. Ghrelin antagonist administration in the latter half of the PPC (LH-PPC) attenuated gastric contraction prolonged the duration of occurrence of PPGC, as found in PII-MMC. CONCLUSION: It is thought that the first half of the PPC changed to PII-MMC and then terminated with PIII-MMC, suggesting that PPC consists of a digestive phase (the first half of the PPC) and a discharge phase (LH-PPC) and that LH-PPC is coincident with MMC. In this study, we propose a new approach for the understanding of postprandial contractions.

Validation of SmartPill® wireless motility capsule for gastrointestinal transit time: Intra-subject variability, software accuracy and comparison with video capsule endoscopy.

BACKGROUND: There is interest in ultimately combining endoscopy and motility assessments. Gastric emptying (GET), small bowel (SBTT), colon (CTT) and whole gut transit (WGTT) times are conveniently obtained by SmartPill® wireless motility capsule (WMC) that records luminal pH, temperature and pressure. Reproducibility within same subjects and accuracy of software derived times (MotiliGI® ) were investigated for diagnostic application. GET and SBTT were separately measured using video capsule endoscopy (VCE). The aim of this investigation was to assess same subject reproducibility of WMC, accuracy of software derived transit times and relate to Pillcam® SB (small bowel) VCE motility data. METHODS: Seventy three healthy adults ingested a 260 kcal mixed meal followed by WMC tests. Food intake was permitted after 6 hours. Regional transit data was obtained for GET, SBTT and CTT, the sum yielding WGTT. Nineteen subjects repeated WMC tests 2 or 4 weeks later; a separate 70 underwent VCE while fasted. KEY RESULTS: Visually derived data from WMC yielded GET 3.46±0.27, SBTT 5.15±0.21, CTT 20.76±1.19 and WGTT 29.53±1.28 hours (mean±SEM). Pearson's correlation coefficients (r) against software derived results were: GET 0.78 (P<.0001), SBTT 0.28 (P<.05), CTT 0.96 (P<.0001), WGTT 0.99 (P<.0001). VCE yielded lower GET (0.71±0.08 hours) and SBTT (4.15±0.13 hours). CONCLUSIONS AND INFERENCES: GET, SBTT, CTT and WGTT obtained by WMC are commensurate with literature values, including by other methods. Visually and software derived transit times have strongest correlations for CTT and WGTT. WMC yields longer GET and SBTT than VCE, perhaps due to meal related effects on motility.