Abdominal accommodation induced by meal ingestion: differential responses to gastric and colonic volume loads

Background Using an experimental model of colonic gas infusion, we previously showed that the abdominal walls adapt to its content by an active phenomenon of abdominal accommodation. We now hypothesized that abdominal accommodation is a physiological phenomenon, and aimed to confirm that it can be induced by ingestion of a meal; a secondary aim was to determine whether the response to gut filling is region-specific. Methods In healthy subjects (n=24) a nutrient test meal was administered until tolerated at a rate of 50mL min1. Electromyographic (EMG) activity of the anterior wall (upper and lower rectus, external and internal oblique) was measured via four pairs of surface electrodes, and EMG activity of the diaphragm via intraluminalelectrodes on an esophageal tube. To address the secondary aim, the response to gastric filling was compared with that induced by colonic filling (1440mL 30min1 anal gas infusion; n=8). Key Results Participants tolerated 927 +/- 66mL of meal (4501500mL). Meal ingestion induced progressive diaphragmatic relaxation (EMG reductionby 16 +/- 2%; P<0.01) and selective contraction of the upper abdominal wall (24 +/- 2% increasein activity of the upper rectus and external oblique; P<0.01 for both), with no significantchangesin the lower rectus (4 +/- 2%)or internal oblique (5 +/- 3%). Colonic gas infusion induced a similar response, but with an overall contraction of the anterior wall. Conclusions & Inferences Meal ingestion induces a metered and region-specific response of the abdominal walls to accommodate the volume load. Abnormal abdominal accommodation could be involved in postprandial bloating.