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Cadmium uptake in rat hepatocytes in relation to speciation and to complexation with metallothionein and albumin.

Pham, T. N. D.; Ségui, J. A.; Fortin, Claude; Campbell, Peter G. C.; Denizeau, Francine; Jumarie, Catherine (2004). Cadmium uptake in rat hepatocytes in relation to speciation and to complexation with metallothionein and albumin. Journal of Cellular Physiology , vol. 201 , nº 2. p. 320-330. DOI: 10.1002/jcp.20063.

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Résumé

Cadmium (Cd) uptake has been studied in primary cultures of rat hepatocytes focusing on the impact of inorganic and organic speciation. Uptake time‐course studies over a 60‐min exposure to 0.3 μM 109Cd revealed a zero‐time uptake and a slower process of accumulation which proceeds within minutes. 109Cd uptake showed saturation kinetics (Km = 3.5 ± 0.8 μM), and was highly sensitive to inhibition by Zn and Hg. There was no evidence for sensitivity to the external pH nor for any preferential transport of the free cation Cd2+ over CdCln2–n chloro‐complexes. According to the assumption that only inorganic metal species are available, metal uptake decreased upon albumin (BSA) addition to the exposure media. In contrast, higher levels of 109Cd accumulation were obtained under optimal conditions for Cd complexation by MT. Comparison among uptake data obtained under inorganic and organic conditions revealed that Cd‐MT would be taken up 0.4 times as rapidly as Cdinorg. We conclude that uptake of Cd in rat hepatocytes involves specific transport mechanism(s) subjected to Zn or Hg interactions. Uptake of inorganic Cd is not proportional to the levels of free Cd2+ and does not involve the divalent cation transporter DCT1 nor the co‐transporter Fe2+‐H+ NRAMP2. We found Cd‐MT but not Cd‐BSA to be available for the liver cells, and have estimated a binding affinity four orders of magnitude higher for Cd complexation with MT compared to BSA; MT may have a significant role in Cd delivery to the liver.

Type de document: Article
Mots-clés libres: albumins; animals; biological transport; cadmium; cells, cultured; hepatocytes; kinetics; metallothionein; organometallic compounds; rats
Centre: Centre Eau Terre Environnement
Date de dépôt: 11 janv. 2021 16:11
Dernière modification: 11 janv. 2021 16:11
URI: http://espace.inrs.ca/id/eprint/11025

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