NEW METHODOLOGY FOR EVALUATION OF RENAL DAMAGE CAUSED BY HEAVY METALS ON THE TUBULAR LEVEL

由镉和汞等重金属引起的肾损害以近端肾小管功能障碍为特征。然而，我们发现可以被这些金属诱导并对这些金属解毒的金属硫蛋白在肾元的远端部分更为丰富。利用一种新颖的同步辐射x射线荧光分析，具有足够的分辨率来定位特定细胞中的金属，我们可以确定肾组织切片中的重金属定位。我们还利用地高辛标记的核糖探针建立了金属硫蛋白mRNA的原位杂交。然后，我们研究了镉和汞处理大鼠肾脏标本中重金属、金属硫蛋白及其mRNA的分布关系。通过金属硫蛋白的原位杂交和免疫组织化学，我们发现金属硫蛋白及其mRNA在近端和远端小管细胞中以不同的方式定位，这表明使用这两种方法有助于识别特定细胞，在特定细胞中合成和/或运输特定蛋白质。

Renal damage that is caused by heavy metals like cadmium and mercury has been characterized by proximal tubular dysfunction. However, we have found that metallothionein, the protein of which can be inducible by these metals and detoxify these metals is present more abundant in distal portions of nephrons. Using a novel synchrotron radiation X-ray fluorescence analysis with sufficient resolution to locate metals in specific cells, we could determine heavy metal localization in renal tissue sections. We also established in situ hybridization of metallothionein mRNA using digoxigenin-labeled riboprobe. Then, we have studied relationships between distributions of heavy metals, metallothionein and its mRNA in cadmium and mercury treated rat kidney specimens. By using in situ hybridization and immunohistochemisry of metallothionein, we have found that metallothionein and its mRNA localize in different manners in proximal and distal tubular cells, suggesting that the use of these two methods is useful in identifying the specific cells where synthesis and/or transport of a particular protein occurs.