Effect of removal of pancreaticobiliary secretions on adaptation to short bowel in orally nourished rats.

To evaluate the need for intraluminal pancreaticobiliary secretions for mucosal adaptation in animals with short bowel, groups of paired rats were prepared with: 1) normal bowel length, 2) 60% proximal small bowel bypass, and 3) similar bypass of distal bowel. One animal in each pair underwent operative diversion of pancreaticobiliary secretions to distal (group 1) or bypassed intestine (groups 2 and 3). Rats were fed an elemental diet and killed 1 month later. Mucosal wet weight, protein content, and DNA content were measured in comparable segments of proximal jejunum and mid-small bowel. Within each group the patterns of response of the three measures of mucosal mass were similar. Group 1: removal of secretions was associated with a 20 to 30% increase in mass in both segments. Group 2: after proximal bypass, mass doubled in mid-small bowel (in continuity) whether or not pancreaticobiliary secretions were removed. Group 3: after distal bypass, no change in mass was apparent in the jejunum even with removal of secretions. We conclude that intraluminal pancreaticobiliary secretions are not required for maintenance of mucosal mass or adaptation to short bowel in animals fed an elemental diet.