SEQUENTIAL ALTERATIONS IN GUT MUCOSAL AMINO-ACID AND GLUCOSE-TRANSPORT AFTER 70-PERCENT SMALL-BOWEL RESECTION

Background. Studied in animals with short bowel syndrome (SBS) suggest that up-regulation of nutrient transporter activity occurs as an adap tive response to the loss of absorptive area. It is unclear, however, whether nutrient transport is altered at the cell membrane in SBS. The purpose of this study is to clarify amino acid and glucose transport in small intestinal huminal mucosa after 70% small bowel resection in rabbits. Methods. New Zealand white rabbits underwent 70% jejunoileal resection (n = 27) or a sham operation (n = 19). Brush border membrane vesicles were prepared from small intestinal mucosa at 1 week, 1 mont h, and 3 months by magnesium aggregation-differential centrifugation. Transport of L-glutamine, L-alanine, L-leucine, L-arginne, and D-gluco se was assayed by a rapid mixing filtration technique. Results. We obs erved no difference in uptake of all amino acids and glucose at 1 week . The uptake of amino acids and glucose was decreased by 20% to 80% in animals with SBS at 1 month. By 3 months all uptake values except tha t of glucose returned to normal. Kinetic studies of the system B trans porter for glutamine indicate that the decrease in uptake at 1 month w as caused by a reduction in the Vmax (1575 +/- 146 versus 2366 +/- 235 , p < 0.05) consistent with a decrease in the number of functional car riers on the brush border membrane. Conclusions. In addition to the an atomic loss of absorptive area after massive bowel resection, alterati ons in enterocyte transport function may be responsible for malabsorpt ion in patients with SBS.