Abstract
Aim: Mosapride, selective 5-HT4 receptor agonist, and itopride, selective D2 receptor antagonist, were known to enhance motility of the distal stomach and facilitate gastric empting. On the other hand, sumatriptan, selective 5-HT1 receptor agonist, and paroxetine, 5-HT reuptake inhibitor, were reported to induce a relaxation in the proximal stomach. In this study, effects of these four drugs on proximal gastric tone were researched using a barostat in conscious dogs with a gastric fistula. Methods: The effects of the drugs and those vehicles on the proximal gastric volume at a constant intragastric tone were studied using a barostat. Simultaneously, proximal and distal gastric contractility, and duodenal contractility was measured using three force transducers. Furthermore, stepwise isobaric gastric distensions were performed before and after the administration of the drugs. The same experiments were done in fasting phase and in postprandial phase. Results & Conclusion: Effects of the drugs on proximal gastric tone were more clearly seen in postprandial phase than fasting phase, and sometimes differed from those on distal gastric and duodenal contractility. Such a measurement of proximal gastric tone using a barostat in animal experiments seems to be useful for estimation of effectiveness of some drug on gastrointestinal disorders. [J Physiol Sci. 2006;56 Suppl:S142]
