In vivo zinc transport by rat small intestine after extensive small bowel resection

We studied the effects of intestinal resection on in vivo zinc transport and intestinal tissue zinc in remnant duodenum and ileum 4 wk after two-thirds small bowel enterectomy. In situ duodenal and ileal intestinal segments from resected and sham-operated control rats were perfused through the lumen with an isotonic solution containing 0.077 mM zinc with isotopic 65Zn as tracer. After resection there was significant mucosal growth in both segments, but segment transport specific activities (transport per gram mucosa) were unchanged. Therefore, increased segment transport capacities (transport per centimeter segment length) in both segments approximated increased mucosal mass. Comparisons with transport data from our earlier studies on other luminal substrates in rats after small bowel resection showed that adaptive transport mechanisms vary not only with the luminal substrate examined but may also differ in remaining proximal and distal small bowel. In the present study about 12% of the absorbed radiotracer zinc remained in the intestinal wall after perfusion of both duodenum and ileum of resected and control animals, and there were no effects of resection on tissue radiotracer 65Zn concentrations or specific activities in the mucosal fraction or underlying tissues. Calculations of mucosal entry and exit fluxes per centimeter segment length showed that the major effect of resection was to increase the zinc entry flux at the luminal surface of the mucosa. At the basal surface of the mucosa, both entry and exit fluxes increased.(ABSTRACT TRUNCATED AT 250 WORDS)