INTESTINAL-ABSORPTION OF CD INVITRO

Everted gut sacs from the rat were utilized to characterize the movement of Cd across the intestinal tract. Total uptake of Cd (tissue content plus serosal fluid content) after incubation for 30 min as a function of the Cd concentration in mucosal fluid (range 5 μm to 3.4 mm) exhibited first-order kinetics. However, tissue Cd concentrations approached a steady state (1-5 μm Cd/g tissue) within 30-min incubation with mucosal concentrations greater than 1.2 × 10-4 m. Serosal fluid demonstrated an increased rate of accumulation of Cd at the higher mucosal fluid concentrations. This increased rate preceded the attainment of a steady state in tissue Cd by approximately 10 min. These results are consistent with the hypothesis that Cd diffuses into the intestinal tissue where part is bound and the remainder passes into the serosal fluid. As the tissue concentration of Cd approaches a steady state, increasing amounts of Cd move into the serosal fluid. © 1979.