Victery W, Miller C R, Zhu S Y, Goyer R A
Fundam Appl Toxicol. 1987 May;8(4):506-16. doi: 10.1016/0272-0590(87)90136-9.
Influence of lead on tissue content and urinary excretion of lead, zinc, and calcium in rats was studied following various exposure periods. Weanling male rats were fed a trace mineral-sufficient diet with either 0, 200, 500, or 1000 ppm lead (as acetate) in drinking water for 4, 8, or 12 weeks. Blood lead ranged from 40 to over 100 micrograms/dl; kidney lead was highest at 4 weeks. Urinary lead excretion was highest at 4 weeks and declined with longer exposure. Urinary zinc excretion correlated positively with lead excretion at the lower excretion rates but plateaued at higher lead excretion rates. After 12 weeks exposure at each lead dose employed, decrease zinc concentration was observed in testes, bone, and brain. Plasma, erythrocyte, and kidney zinc were not affected, while pancreas and liver zinc were slightly elevated. Urine calcium was increased significantly only in rats exposed to 1000 ppm, possibly reflecting renal cell damage as determined by elevated renal calcium levels. These results indicate that lead dose is more important than exposure period for determining kidney lead levels, while urinary lead excretion rate is both dose and time dependent. Blood lead clearance values are relatively independent of dose and fall as exposure continues. Essential trace metal balance for zinc, especially, and to a lesser extent for calcium, is affected by the dose and length of chronic lead exposure.
在不同暴露时间段后，研究了铅对大鼠体内铅、锌和钙的组织含量及尿排泄的影响。将断乳雄性大鼠喂以含微量矿物质充足的饲料，饮水中添加0、200、500或1000 ppm的铅（以醋酸盐形式），持续4、8或12周。血铅范围为40至超过100微克/分升；肾脏铅含量在4周时最高。尿铅排泄在4周时最高，并随着暴露时间延长而下降。在较低排泄率时，尿锌排泄与铅排泄呈正相关，但在较高铅排泄率时趋于平稳。在每个所用铅剂量下暴露12周后，观察到睾丸、骨骼和大脑中的锌浓度降低。血浆、红细胞和肾脏中的锌未受影响，而胰腺和肝脏中的锌略有升高。仅在暴露于1000 ppm的大鼠中，尿钙显著增加，这可能反映了肾钙水平升高所确定的肾细胞损伤。这些结果表明，在确定肾脏铅水平方面，铅剂量比暴露时间段更重要，而尿铅排泄率既取决于剂量也取决于时间。血铅清除值相对独立于剂量，并随着暴露持续而下降。尤其是锌，在较小程度上钙的必需微量元素平衡受到慢性铅暴露的剂量和时长的影响。
