Our aim was to evaluate the short-term effect of a reversed segment on structural and functional intestinal adaptation. Ten dogs underwent 75% distal resection and serosal electrode placement with (RS, n = 5) or without (RO, n = 5) reversal of the terminal 10 cm of the remnant. Nutritional status, absorption, motility, hormonal response, and remnant adaptation were studied at 4, 8, and 12 weeks. Both groups lost weight (RO 89 ± 3% and RS 76 ± 8% of initial wt at 12 weeks). Hypoalbuminemia occurred in the RS animals (2.5 ± .4 vs 2.9 ± 4 g/dl, P < 0.05). Caloric intake was lower in RS animals during the first 2 weeks. Stool weight increased transiently (4 and 8 weeks) after RO (239 ± 92 and 249 ± 25 g/day vs 101 ± 42 g/day, preop, P < .05) but not RS, Stool fat was elevated in both groups. Remnant length increased after RO (90 ± 16 to 110 ± 21 cm) but not after RS (89 ± 8 vs 86 ± 9 cm). Morphometric changes were similar. Plasma PYY was increased after RO but not RS animals. Changes in tissue neuropeptides were similar. Intestinal transit time was increased 4 weeks after RS (19 ± 9 vs 10 ± 2 min) but was similar to RO thereafter. Myoelectrical activity in the reversed segment was persistently reversed and independent; only 11% of proximal Phase 3 complexes were propagated into the reversed segment. The dominant motor pattern within this segment was orad-migrating clusters and prolonged spike bursts. Rapidly migrating myoelectrical events, perhaps consequent on the obstructive effect of the reversed segment, were also noted throughout the small intestine in RS animals. Reversed segments ameliorate diarrhea but impair nutritional status in the short term. The intestinal adaptive response is blunted. The changes in RS relate to transiently decreased caloric intake, lack of hormonal responses, and altered myoelectrical activity.
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