INFLUENCE OF LOW LUMINAL CADMIUM-CONCENTRATIONS ON TRANSFER OF WATER AND CADMIUM IN THE RAT SMALL-INTESTINE INVITRO

The sensitivity of the small intestinal water transfer for cadmium (Cd ) exposure and its longitudinal gradient were investigated in luminall y perfused intestinal segments in vitro and in vivo. Proximal segments accumulated Cd to a higher extent and, in addition, were more sensiti ve to Cd exposure than distal segments. In the proximal small intestin e Cd impairs the intestinal water transfer at concentrations between 0 .1 and 1.0 mumol/l in vitro and 4 mumol Cd/l in vivo. In vitro the Cd transfer from the intestinal tissue into the serosal absorbate decline d in parallel to the reduction of the water transfer. In proximal but not in distal segments the declining water transfer corresponded to th e decreases in glucose transfer in response to Cd exposure. According to literature the Cd effect on intestinal water transfer may be mediat ed by interaction of Cd with the Na-glucose co-carrier or by inhibitio n of the oxidative phosphorylation. The involvement of both mechanisms may differ along the small intestine.