Gastrointestinal absorption of Cd-metallothionein and cadmium chloride in mice.
CdCl2 or Cd-metallothionein (MT) (6 micrograms Cd with 2.25 muCi (83.25 KBq) 109Cd) was given orally to mice, which were sacrificed at 30 min and 2 h after intubation. Although 109Cd 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.
Sugawara
N
N
Department of Public Health, Sapporo Medical College, Japan.
Sugawara
C
C
D000818:Animals; D002104:Cadmium / Q000493:pharmacokinetics*; D019256:Cadmium Chloride; D007408:Intestinal Absorption; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008668:Metallothionein / Q000493:pharmacokinetics*; D051379:Mice; D008813:Mice, Inbred ICR
C004203:cadmium-binding protein; D002104:Cadmium; D008668:Metallothionein; D019256:Cadmium Chloride