Gagnon E, Hontela A, Jumarie C
Département des sciences biologiques, centre TOXEN, Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montréal, Québec, Canada H3C 3P8.
Toxicol In Vitro. 2007 Sep;21(6):1077-86. doi: 10.1016/j.tiv.2007.03.019. Epub 2007 Apr 14.
Some environmental pollutants, including cadmium (Cd) and zinc (Zn), can act as endocrine disruptors in fish, either in vivo or through a direct action on steroidogenic cells, as has been demonstrated in vitro. We have previously characterized Cd uptake in head kidney (homologue of mammalian adrenal) cells of rainbow trout (Oncorhynchus mykiss) and have provided evidence for a Cd/Ca interaction. Here, we pursued our investigation of metal competition for uptake. Our results show that inorganic speciation conditions favour Cd uptake with optimal level of accumulation for Cd2+ compared to chlorocomplexes (CdCl(n)(2-n)). Calcium uptake was studied for the first time in the fish head kidney cells and Ca was found to be less efficiently accumulated compared to Cd. A specific saturable mechanism of transport was characterized for Ca uptake but voltage-gated or La-sensitive cationic channels are unlikely to contribute appreciably. A concentration-dependent reciprocal inhibition was observed between Ca and Cd, whereas, Zn proved to inhibit Cd uptake exclusively. Additive inhibitory effect on Cd uptake was obtained with co-exposure to Ca and Zn. We conclude that Cd, but not Zn, may decrease Ca availability to the head kidney tissue. Also, Zn may partially protect against Cd toxicity but Zn would not protect against Cd-induced perturbation of Ca homeostasis.
一些环境污染物，包括镉（Cd）和锌（Zn），在鱼类体内或通过对类固醇生成细胞的直接作用，可作为内分泌干扰物，这在体外实验中已得到证实。我们之前已对虹鳟（Oncorhynchus mykiss）头肾（相当于哺乳动物的肾上腺）细胞对镉的摄取进行了表征，并提供了镉/钙相互作用的证据。在此，我们继续研究金属摄取的竞争情况。我们的结果表明，无机形态条件有利于镉的摄取，与氯络合物（CdCl(n)(2-n)）相比，Cd2+的积累水平最佳。首次在鱼头肾细胞中研究了钙的摄取，发现与镉相比，钙的积累效率较低。已确定钙摄取存在一种特定的可饱和转运机制，但电压门控或镧敏感阳离子通道不太可能起显著作用。在钙和镉之间观察到浓度依赖性的相互抑制，而锌仅抑制镉的摄取。同时暴露于钙和锌对镉的摄取产生了相加抑制作用。我们得出结论，镉而非锌可能会降低头肾组织对钙的可利用性。此外，锌可能部分预防镉的毒性，但锌无法预防镉诱导的钙稳态紊乱。
