Ileal short-chain fatty acids inhibit transpyloric flow in pigs

BACKGROUND: Short-chain fatty acids (SCFA) found in the ileum after caecoileal reflux might trigger a physiologic ileal brake similar that induced by ileal nutrient infusion. This study evaluates gastric emptying and motility after ileal administration of SCFA. METHODS: In eight conscious pigs gastric emptying was evaluated by double dilution (liquids) and direct measurement of duodenal effluent (liquids and solids) during ileal infusions of SCFA and isotonic and hypertonic saline. Antropyloroduodenal manometry and flow were recorded concurrently. RESULTS: Ileal SCFA significantly delayed gastric emptying of liquids and solids. During SCFA infusion the emptying pattern of liquids was less pulsatile, and flow pulses had a smaller stroke volume than during isotonic saline. The antroduodenal pressure gradient was decreased, whereas pyloric tone was increased. A reduced number of antral pressure waves occurred together with an increased frequency of isolated pyloric pressure waves. CONCLUSIONS: Ileal SCFA infusion delays gastric emptying of liquid and solid as a consequence of a decreased antral and increased pyloric motility.