Glucose transport by rat small intestine after extensive small-bowel resection

In rats 50 cm of proximal or distal small intestine were resected, preserving duodenum and terminal ileum. Glucose transport was studied 5–6 weeks later, using everted gut sacs from duodenum, ileum, and also from a midgut segment consisting of intestine located preresection at mid-small intestine. Sham-operated animals served as controls: The inner (serosal) fluid medium in sacs from duodenum and midgut gained glucose; ileal sac serosal medium lost glucose. Proximal resection resulted in significant growth of duodenal and midgut mucosa. Duodenal transport specific activity (transport per gram dry mucosa) decreased from control values, but mucosal growth compensated so sac transport capacity (transport per centimeter sac length) remained unchanged. Midgut transport specific activity remained unchanged, thus sac transport capacity directly mirrored increased mucosal mass. Ileal sac serosal medium now accumulated glucose; there was no mucosal growth. Transport specific activity and sac transport capacity of ileum increased in parallel. After distal resection there was no alteration of either duodenal and midgut mucosal masses or transport specific activities, hence sac transport capacities remained unchanged. Ileal sac serosal medium also accumulated glucose, but now both transport specific activity and mucosal mass increased. The resultant increased sac transport capacity was identical to that of ileum after proximal resection. In all sacs from control and resected animals uphill ¹⁴C]glucose concentration differences developed between medium and mucosa. Activity of the mucosal uptake process, assessed in terms of a ratio of mucosal intracellular fluid radioactivity to mucosal medium radioactivity, usually mirrored altered transport specific activity. This indicates that the increased undercoats tissue mass that accompanied increased mucosal mass did not critically affect transport. The most striking findings were: (1) decreased duodenal transport specific activity after proximal resection with mucosal growth compensating; and (2) identical adaptations of ileal segment transport capacities after either proximal or distal small-bowel resections, although mechanisms differed. The present study provides a base for further examinations of carrier-mediated hexose transport after extensive loss of small intestine.