Indigestible disaccharides open tight junctions and enhance net calcium, magnesium, and zinc absorption in isolated rat small and large intestinal epithelium

The effects of three indigestible disaccharides on net calcium (Ca), magnesium (Mg), and zinc (Zn) transport in isolated rat jejunal, ileal, cecal, and colonic epithelium were determined. Permeability of fluorescein isothiocynate-dextran-4 (FD4) and transepithelial electrical resistance ( TEER), which vary according to tight junction (TJ) activity in the intestinal mucosa, were also determined. The addition of 1-100 mM melibiose, difructose anhydride (DFA) III, or DFA IV to the mucosal medium increased the net absorption of the three minerals and FD4 permeability, while decreasing TEER dose dependently in the four intestinal portions. Positive linear relations were found between the net transport of the three minerals and FD4 passage in all portions of the intestine, whereas negative linear relations were observed between net absorption of the three minerals and TEER. We concluded that the three indigestible saccharides directly affect the epithelial tissue and open TJs, thereby promoting Ca, Mg, and Zn absorption in the small and large intestine in vitro.