Small Bowel Adaptation Is Dependent on Site of Massive Enterectomy

Abstract

Background.Changes in amino acid transport after massive enterectomy occur in a nutrient-dependent fashion and may affect long-term outcome. Epidermal growth factor (EGF) can enhance nutrient transport and a defective epidermal growth factor receptor (EGF-R) has been noted to attenuate adaptation. Most animal studies, however, have examined only a single site of resection. This does not mimic the clinical situation where disease dictates the site of resection leading to proximal, middle, or distal enterectomies. We hypothesize that the site of massive enterectomy will alter nutrient transport and EGF-R levels in the residual gut.Materials and methods.New Zealand White rabbits were randomized to control, midgut division, or 70% resection (proximal, midgut, or distal). After 1 week, sodium-dependent transport of glucose, glutamine, alanine, and leucine into brush border membrane vesicles was quantitated. EGF-R protein was determined by Western blot analysis.Results.At baseline, amino acid transport was greater in ileum than jejunum. Surgery alone elevated glutamine and leucine jejunal transport by 130 and 97%, respectively, over controls (P< 0.05). Midgut resection increased jejunal glutamine transport 61% over control (P< 0.05). In contrast, distal resection increased jejunal alanine transport by 150% over controls with no change in glutamine (P< 0.05). After midgut resection, EGF-R was significantly greater (124%) in ileum then in jejunum in whole mucosa homogenates. Proximal resection significantly lowered ileal EGF-R compared to that seen in midgut resected residual ileum.Conclusions.Site of massive resection is important in determining postoperative changes in nutrient transport and EGF-R.