Factors affecting outcome following proximal and distal intestinal resection in the dog - An examination of the relative roles of mucosal adaptation,motility, luminal factors, and enteric peptides

In the clinical setting, resection of the ileum results in an inferior func tional outcome compared to jejunal resection. This may be related to a grea ter adaptive capacity of the ileum, intrinsic structural and functional dif ferences, or regional differences in motor and hormonal function. Our aim w as to evaluate the relative contributions of these factors to functional ou tcome after resection of the proximal or distal intestine. Twenty-four dogs underwent either intestinal transection or 50% resection of the proximal o r distal intestine. Studies (nutritional status, absorption, adaptation, mo tility, peptide levels) were performed every four weeks until the animals w ere killed at 12 weeks. Caloric intake was similar in all four groups. Weig ht loss was greater and more sustained after distal resection (DR). Serum c holesterol levels decreased significantly only in the DR group. While stool weight and moisture were similar, the DR animals had persistent, significa nt steatorrhea. Intraluminal anaerobic bacteria and SCFA concentrations wer e significantly greater in the ileum but were not influenced by resection. Intestinal remnant length increased to a greater extent after proximal rese ction (PR), but circumference increased to a similar extent after both rese ctions. Villus height and crypt depth increased significantly only after PR . MMC frequency was similar in all four groups. In the DR animals 26% of mi grating motor complexes (MMCs) originated within the remnant. The jejunal r emnant of these animals had a dominance of cluster activity similar to the intact distal ileum. Following PR, the postprandial motilin response was de creased. After DR, there were transient increases in neurotensin and PYY. O f the various factors evaluated, mucosal adaptation and the intestinal moto r response appear most likely to explain the inferior nutritional and absor ptive outcome associated with resection of the distal small intestine.