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 rec ipient's abdominal cavity are the main factors to be considered in the segmental transplantation of the small intestine. It was the aim of t he following study to gain insight into the functional characteristics of different portions of the small intestine either after partial res ection or syngeneic and allogeneic transplantation during the early po stoperative period. Nutritional parameters (serum albumin levels, seru m 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 deat hs were due to ileus or pneumonia. After allotransplantation, cyclospo rine (15 mg/kg BW s.c.) was administered for graft acceptance. Control s were unoperated, weight- and age-matched Lewis rats (n = 7). We foun d that resection of two-thirds of the small intestine led to significa ntly lower levels of albumin and triglycerides in all the three portio ns investigated (P < 0.01) but did not affect maltose absorption. Excr etion of fecal fat was elevated after distal resection (P < 0.05). Whe n compared to resected animals, syngeneic transplantation did not affe ct the nutritional parameters, but caused a significantly higher hormo ne release (P < 0.05) in all three different intestinal grafts. Alloge neic transplantation was successful when the middle or distal portion was grafted. All recipients of proximal allografts showed a severe los s of body weight and died between day 8 and 10 after transplantation. Postmortem examination revealed no signs of acute rejection. When tran splantation of short intestinal segments is considered, it is of vital importance to take into account the functional differences and the in fluence of immunosuppressive drug therapy in the regulatory bowel func tion.