The adaptive response of the rat small intestine after resection and segmental transplantation during the early postoperative phase

Organ harvesting from a living donor or spatial constraints in the recipient's abdominal cavity are the main factors to be considered in the segmental transplantation of the small intestine. It was the aim of the following study to gain insight into the functional characteristics of different portions of the small intestine either after partial resection or syngeneic and allogeneic transplantation during the early postoperative period. Nutritional parameters (serum albumin levels, serum triglyceride levels, maltose absorption, excretion of fecal fat) and fat-stimulated neurotensin release were determined in Lewis rats that underwent small bowel resection (n = 21), syngeneic (Lewis-->Lewis, n = 21), or allogeneic transplantation (Brown Norway-->Lewis, n = 24). The length of the remnant, isograft, or allograft was 27 cm (i.e. one third of the rat small intestine) and consisted of the proximal (n = 7), middle (n = 7), or distal (n = 7) portion. Three postoperative deaths were due to ileus or pneumonia. After allotransplantation, cyclosporine (15 mg/kg BW s.c.) was administered for graft acceptance. Controls were unoperated, weight- and age-matched Lewis rats (n = 7). We found that resection of two-thirds of the small intestine led to significantly lower levels of albumin and triglycerides in all the three portions investigated (P < 0.01) but did not affect maltose absorption. Excretion of fecal fat was elevated after distal resection (P < 0.05). When compared to resected animals, syngeneic transplantation did not affect the nutritional parameters, but caused a significantly higher hormone release (P < 0.05) in all three different intestinal grafts. Allogeneic transplantation was successful when the middle or distal portion was grafted. All recipients of proximal allografts showed a severe loss of body weight and died between day 8 and 10 after transplantation. Postmortem examination revealed no signs of acute rejection. When transplantation of short intestinal segments is considered, it is of vital importance to take into account the functional differences and the influence of immunosuppressive drug therapy in the regulatory bowel function.