Effects of ethanol, xylose, and glucose on canine jejunal motility

Ethanol is an important source of calories that can cause certain gastrointestinal symptoms, notably diarrhea. To examine the effects of ethanol on the small bowel, we intraluminally perfused the jejunum of four dogs with ethanol (18, 9, 4.5, and 1.5%, wt/vol), D-xylose (30, 15, 7.5, and 4.5%, wt/vol), or glucose (30 and 5%, wt/vol). In other experiments, these solutes were infused intravenously. Saline was always given by the alternate route; jejunal manometry was recorded during and after the infusions. Phase III of the interdigestive cycle was delayed by all intraluminal infusions except for 4.5 and 1.5% ethanol, 4.5% xylose, and 5% glucose. In addition, the onset of irregular contractile activity was delayed more with intraluminal ethanol than with intraluminal xylose or intraluminal glucose (P < 0.01). When administered intraluminally, ethanol and xylose appeared in blood but only ethanol equilibrated fully between the lumen and blood. Intravenous infusions of ethanol and xylose, but not glucose, also delayed the return of phase III. When given intravenously, ethanol and xylose were recovered from the lumen, whereas glucose never was. Ethanol and xylose had comparable effects on the canine small bowel; they induced prolonged periods of irregular contractile activity and delayed the return of phase III. These effects were seen rapidly when solutes were administered intraluminally and more slowly when they were given intravenously. These results suggest that local luminal mechanisms stimulated by solutes influence small bowel motility, and they imply that the gut recognizes solutes whether or not these molecules are metabolizable.