In vitro analysis of the bioavailability of six metals via the gastro-intestinal tract of the rainbow trout (Oncorhynchus mykiss).
In vitro analysis of the bioavailability of six metals via the gastro-intestinal tract of the rainbow trout (Oncorhynchus mykiss).
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DOI：
10.1016/j.aquatox.2007.03.006
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发表时间：
2007-06
影响因子：
4.5
通讯作者：
A. Ojo;C. Wood
中科院分区：
文献类型：
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作者：
A. Ojo;C. Wood
采用体外肠囊技术比较了淡水虹鳟鱼胃肠道（胃、前肠、中肠和后肠）四个部分在管腔盐水中50μmolL− 1（食糜溶液中的典型营养水平）的必需金属（铜、锌和镍）和非必需金属（银、镉和铅）的吸收率。铜，锌，镉和银表现出类似的区域模式：在特定区域的基础上，这些金属的吸收率最高的前肠，最低的胃，大约相等的中间和后肠段。当将这些比率转换为整个动物基础时，前肠的优势增加，因为其面积更大，而胃的贡献略微上升，接近中肠和后肠的贡献。然而，对于铅和镍，特定区域和整个有机体的运输率是最大的中间（铅）和后部（镍）肠。令人惊讶的是，总迁移率在必需和非必需金属之间没有明显差异，仅在0.025（Ag）至0.050 nmolg −1h−1（Ni）之间变化，这表明单一速率常数可用于风险评估目的。这些速率通常与先前报道的在低1-4个数量级的浓度下进行的水暴露的摄取速率相当，表明这两种途径可能都很重要，并且肠道转运蛋白的亲和力比鳃转运蛋白低得多。除了镍，更多的金属被绑定到粘液和/或被困在粘膜上皮比被运送到血液空间中的每一个隔室，除了前肠，其中净运输占主导地位。总体而言，粘液结合是一个显着的预测净转运率的每一种金属，但镉，铅和最强的关系。
An in vitro gut sac technique was used to compare the uptake rates of essential (copper, zinc and nickel) and non-essential metals (silver, cadmium and lead) at 50μmolL−1each (a typical nutritive level in solution in chyme) in the luminal saline in four sections of the gastro-intestinal tract (stomach, anterior, mid and posterior intestines) of the freshwater rainbow trout. Cu, Zn, Cd and Ag exhibited similar regional patterns: on an area-specific basis, uptake rates for these metals were highest in the anterior intestine, lowest in the stomach, and approximately equal in the mid and posterior intestinal segments. When these rates were converted to a whole animal basis, the predominance of the anterior intestine increased because of its greater area, while the contribution of the stomach rose slightly to approach those of the mid and posterior intestines. However, for Pb and Ni, area-specific and whole organism transport rates were greatest in the mid (Pb) and posterior (Ni) intestines. Surprisingly, total transport rates did not differ appreciably among the essential and non-essential metals, varying only from 0.025 (Ag) to 0.050nmolg−1h−1(Ni), suggesting that a single rate constant can be applied for risk assessment purposes. These rates were generally comparable to previously reported uptake rates from waterborne exposures conducted at concentrations 1–4 orders of magnitude lower, indicating that both routes are likely important, and that gut transporters operate with much lower affinity than gill transporters. Except for Ni, more metal was bound to mucus and/or trapped in the mucosal epithelium than was transported into the blood space in every compartment except the anterior intestine, where net transport predominated. Overall, mucus binding was a significant predictor of net transport rate for every metal except Cd, and the strongest relationship was seen for Pb.