Alves L C, Glover C N, Wood C M
Department of Biology, McMaster University, Hamilton, Ontario, Canada, L8S 4K1.
Arch Environ Contam Toxicol. 2006 Nov;51(4):615-25. doi: 10.1007/s00244-005-0212-7. Epub 2006 Sep 23.
Three different diets amended with lead (Pb) nitrate Pb(NO3)2 (7, 77, and 520 microg Pb/g dry weight) and a Pb-free control diet (0.06 microg Pb/g dry weight) were fed to juvenile freshwater rainbow trout for 21 days. Accounting for measured food consumption, the calculated doses per fish were 0.02, 3.7, 39.6, and 221.5 microg/day, for the control, low, intermediate, and high Pb treatments, respectively. The patterns of Pb accumulation over time were determined in various tissues (gills, liver, kidney, intestine, carcass), red blood cells (RBC), and plasma, as well as feeding, growth, hematological, and ionoregulatory parameters. Pb accumulation occurred in a dose-dependent manner in all tissues except the plasma, where accumulation was minimal. Overall, when fed the highest Pb diet, the intestine exhibited the greatest Pb burden (17.8 microg Pb/g tissue wet weight), with high concentrations also found in the kidney (2.4 microg Pb/g tissue wet weight) and liver (1.9 microg Pb/g) at the highest dietary Pb treatment by day 21. The RBCs accumulated a substantial amount of Pb (1.5 microg Pb/g) when compared to the plasma (0.012 microg Pb/g) in the high treatment group. The percentage of Pb retained in the fish decreased with increasing dietary Pb concentrations. Growth, survival, plasma protein, and hematocrit were not significantly affected by dietary Pb. Plasma Ca2+ levels decreased at the beginning of the experiment, whereas Mg2+ levels decreased during the middle of the experiment in both the intermediate and high dietary treatments. Both the Ca2+ and Mg2+ levels stabilized by day 21. Branchial Ca2+ and Na+ influx rates were not affected by dietary Pb, except on day 8 where Na+ influx rates were significantly elevated. The results of this study show that Pb does accumulate internally from the diet when present at levels within the range reported in contaminated benthic invertebrates in nature. We further identify the intestine as a potential target site of chronic toxicity of Pb via the diet, and RBCs as a reservoir of dietary Pb.
用硝酸铅（Pb(NO3)2）（7、77和520微克铅/克干重）改良的三种不同日粮以及一种无铅对照日粮（0.06微克铅/克干重）投喂幼年淡水虹鳟21天。考虑到实测的食物摄入量，计算得出每条鱼每天的剂量分别为：对照、低、中、高铅处理组分别为0.02、3.7、39.6和221.5微克/天。测定了不同组织（鳃、肝脏、肾脏、肠道、鱼体）、红细胞（RBC）和血浆中铅随时间的积累模式，以及摄食、生长、血液学和离子调节参数。除血浆中积累极少外，所有组织中的铅积累均呈剂量依赖性。总体而言，投喂最高铅日粮时，到第21天，肠道中的铅负荷最大（17.8微克铅/克组织湿重），在最高日粮铅处理组中，肾脏（2.4微克铅/克组织湿重）和肝脏（1.9微克铅/克）中也发现高浓度铅。在高处理组中，与血浆（0.012微克铅/克）相比，红细胞积累了大量铅（1.5微克铅/克）。鱼体中保留的铅百分比随日粮铅浓度的增加而降低。日粮铅对生长、存活、血浆蛋白和血细胞比容无显著影响。在实验开始时血浆Ca2+水平下降，而在实验中期，中、高日粮处理组的Mg2+水平下降。到第21天，Ca2+和Mg2+水平均稳定下来。日粮铅对鳃Ca2+和Na+内流速率无影响，但在第8天，Na+内流速率显著升高。本研究结果表明，当铅以自然界受污染底栖无脊椎动物报告范围内的水平存在时，确实会从日粮中在体内积累。我们进一步确定肠道是铅通过日粮产生慢性毒性的潜在靶器官，红细胞是日粮铅的储存库。
