Effect of Enteric Nonnutrient Infusions on Motor Patterns in Neurally Intact and Neurally Isolated Canine Jejunum

Abstract

Previous work in our laboratory has shown that nonnutrient mechanical factors initiate changes in motility patterns in local and remote regions of the small intestine. Our aims were to determine how isolated duodenal and jejunoileal nonnutrient infusions alter interdigestive motor patterns locally and distantly and whether these effects are neurally mediated. Ten dogs were prepared with duodenal and proximal jejunal infusion and manometry catheters and a proximal jejunal diverting cannula. Five of these dogs served as neurally intact controls (Group 1) and five also underwent in situ neural isolation of the entire jejunoileum (Group 2: extrinsic denervation; disruption of enteric myoneural continuity with duodenum). After recovery, nonnutrient infusions at 0-15 ml/min for 5 hr into proximal duodenum or jejunum did not consistently affect cycling of the migrating motor complex (MMC). The period and duration of individual phases of the MMC and time to first phase III after the start of infusion were similar in both groups. In Group 2, duodenal characteristics (period and duration of phase II, time to first phase III) increased slightly with increasing rates of jejunal but not duodenal infusion. Motility indices, although greater in Group 2, were not altered by enteric infusions. Differing rates of nonnutrient enteric flow limited to duodenum or jejunoileum did not affect markedly local or distant motor patterns. Alterations in interdigestive motility patterns by postprandial nonnutrient intraluminal content are not mediated directly by intraluminal flow.