Suzuki Y, Yoshikawa H
J Toxicol Environ Health. 1981 Sep;8(3):479-87. doi: 10.1080/15287398109530084.
The urinary excretion of Cd, Cu, and Zn was measured in rats injected with 0.5 mg/kg Cd, sc, 6 d/wk for u to 25 wk. Gel chromatographic analysis for these urinary metals were also carried out. The Cd excretion slightly increased at first, followed by a rapid increase with concurrent appearance of proteinuria around 6 wk. During these early weeks, excretion of Cu in the urine showed a more pronounced increase and reached a plateau level (three to four times the control value). Zn excretion showed a sharp increase accompanied by proteinuria, following a slight increase, and reached about 10 times the control value. A linear relation was obtained between Cd and both Cu and Zn in the urine before proteinuria appeared. Metallothionein (MT) in the urine was associated only with Cu before the appearance of proteinuria. Cu-MT increased with increasing excretion of urinary Cu. Cd-containing MT first appeared in the urine after on onset of proteinuria, but it was still rich in Cu at first. Fron 10 wk, urinary MT showed an excess increase and contained much Cd than Cu. Zn-MT was not observed in the urine. Most of the urinary Zn was recovered from the lower-molecular-weight fractions. The results suggest that MT is directly involved in urinary excretion of Cu in the absence of renal damage and in the excretion of Cd as well as Cu after the appearance of toxicity in Cd-exposed rats.
对每周皮下注射6天、剂量为0.5毫克/千克镉、持续25周的大鼠，测量其镉、铜和锌的尿排泄量。还对这些尿中金属进行了凝胶色谱分析。镉排泄量起初略有增加，随后迅速增加，约6周时同时出现蛋白尿。在这些早期阶段，尿中铜的排泄量增加更为明显，并达到一个稳定水平（为对照值的三到四倍）。锌排泄量在略有增加后，伴随着蛋白尿急剧增加，达到约为对照值10倍的水平。在蛋白尿出现之前，尿中镉与铜和锌之间呈线性关系。在蛋白尿出现之前，尿中的金属硫蛋白（MT）仅与铜相关。铜-金属硫蛋白随着尿铜排泄量的增加而增加。含镉金属硫蛋白在蛋白尿出现后首次出现在尿中，但起初仍富含铜。从10周起，尿中金属硫蛋白过度增加，且含镉量多于铜。尿中未观察到锌-金属硫蛋白。大部分尿锌从低分子量组分中回收。结果表明，在无肾损伤时，金属硫蛋白直接参与尿铜的排泄，在镉暴露大鼠出现毒性后，金属硫蛋白也参与镉和铜的排泄。
