[Effect of electrical lesion of the area postrema on gastrointestinal interdigestive migrating motor complex in conscious dogs].

OBJECTIVE: To investigate the effect of area postrema (AP) of medulla oblongata on gastrointestinal interdigestive migrating motor complex (MMC). METHODS: Interdigestive MMC activity of antrum and duodenum was recorded by strain gauge implanted on the serosa in 8 conscious dogs. Cannula was intubated in the femoral vein for motilin injection. Plasma motilin concentration was measured by RIA. We observed (1) normal interdigestive MMC activity and fluctuation of plasma motilin concentration; (2) the effect of electrically destroying AP on MMC activity and plasma motilin level and (3) whether or not intravenous injection of motilin could induce phase III contractions after AP was destroyed. RESULTS: (1) Typical interdigestive MMC with phases I, II, III and IV was recorded in normal dogs. Phase III was concurrent with the peak of plasma motilin level. (2) In dogs electrically destroyed AP with antroduodenal interdigestive MMC contractions were suppressed; cyclic, phasic and migratory pattern of MMC was disrupted. Plasma motilin concentration was decreased. Intravenous injection of motilin could not induce phase III contractions. CONCLUSION: Area postrema plays an important role, which is mediated by motilin, on the regulation of interdigestive MMC.