Intestinal Brush Border Alkaline Phosphatase in the Rat after Proximal Small Bowel Resection

In rats 50 cm of proximal intestine were resected with preservation of duodenum and ileum. Mucosal brush border alkaline phosphatase was measured 6-7 weeks later in segments of duodenum, ileum, and a midgut segment located prere-section at mid small intestine. Sham-operated animals served as controls. After resection there was significant mucosal growth in duodenum and midgut. In duodenum brush border alkaline phosphatase specific activity (activity per gram of wet mucosa) decreased, but increased mucosal mass compensated so total enzyme activity (activity per centimeter of intestinal length) did not change. In midgut both enzyme specific activity and total activity increased maximally while in ileum neither enzyme specific activity nor total activity changed. These studies show that brush border alkaline phosphatase undergoes postresection changes but alterations vary with the location of the intestinal segment studied. Comparisons with an earlier study of calcium transport suggest that duodenal brush border alkaline phosphatase may play a role in postresection transport adaptation.