Abstract
CdCl2 or Cd-metallothionein (MT) (6 μg Cd with 2.25 μCi (83.25 KBq)109Cd) was given orally to mice, which were sacrificed at 30 min and 2 h after intubation. Although109Cd in Cd-MT was excreted rapidly into the urine, its absorption was found to be significantly less than that of CdCl2. The poor absorption was due to a decrease of Cd-MT uptake into the intestine. Cadmium chloride taken up into the mucosa could stimulate MT synthesis even 30 min after its intubation. However, the percentage of MT-bound Cd in the Cd of intestinal supernatants was lower with CdCl2 (62% at 30 min and 2 h) than with Cd-MT (78% and 84% at 30 min and 2 h, respectively). These results suggest that the transport mode of lumenal Cd-MT to mucosal cells is different from that of lumenal CdCl2. Lumenal Cd-MT is probably internalized into intestinal cells in an intact form. Furthermore, the Cd-MT may pass through the basolateral membrane in this form. This hypothesis was supported by the different distributions of Cd in the liver and kidney after Cd-MT and CdCl2 intubations.
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Sugawara, N., Sugawara, C. Gastrointestinal absorption of Cd-metallothionein and cadmium chloride in mice. Arch Toxicol 65, 689–692 (1991). https://doi.org/10.1007/BF02098039
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DOI: https://doi.org/10.1007/BF02098039