Effects of Lanthanum, Terbium and Ytterbium on the Absorption of Saccharides in the Small Intestine of Mice.

Abstract

The effects of lanthanum, terbium, and ytterbium on the in situ small intestinal absorption of D-glucose, D-fructose, and maltose in mice were studied. The absorption of D-glucose (11.1 mM), which is actively absorbed from the small intestine in situ, was significantly decreased in the presence of LaCl3 (La) and TbCl3 (Tb) at concentrations of 1, 2 and 4 mM, and YbCl3 (Yb) at concentrations of 2 and 4 mM in the lumen. The absorption of D-fructose (2.75 mM), which is absorbed by facilitated diffusion, was significantly decreased by these metals at the concentration of 4 mM, The absorption of maltose (11.1 mM) was also significantly decreased by these metals at concentrations of 1, 2, and 4 mM. The whole intestinal accumulation of La, Tb, and Yb in the perfusion experiment was great. The activities of Na+, K+-ATPase and maltase in the small intestinal mucosa were significantly decreased by these metals in the in situ perfusion experiment and the in vitro experiment. A scanning electron micrograph of the jejunum after the in situ perfusion experiment with each saccharide plus each metal showed mucosal damage. These results indicate that La, Tb, and Yb cause damage to intestinal mucosa and inhibit the activities of Na+, K+-ATPase and maltase in the intestinal mucosa, resulting in the inhibition of the intestinal absorption of D-glucose, D-fructose, and maltose.