Trevisan A, Cristofori P, Fanelli G
Laboratory of Industrial Toxicology, Institute of Occupational Health, University of Padova, Italy.
Arch Toxicol. 1999 Jun-Jul;73(4-5):255-62. doi: 10.1007/s002040050614.
The possibility of detecting segment-specific injury of the proximal tubule by means of urinary enzymes was investigated in rats. Urinary glutamine synthetase, an enzyme exclusively localized in the S3 segment, and N-acetyl-beta-D-glucosaminidase, prevalently a S1-S2, but S3 enzyme also, were determined after single treatment with 100 mg/kg body wt. of hexachloro-1:3-butadiene (HCBD; i.p.), toxic for the S3 segment, or 25 mg/kg body wt. of potassium dichromate (s.c.), toxic for the S1-S2 segments. Excretion of total urinary proteins was also measured. In addition, a dose-response relationship was determined between three doses (50, 100 and 200 mg/kg body wt.) of HCBD and glutamine synthetase activity in urine. Glutamine synthetase activity, measured according to a new assay for urine based on modification of methods developed for organs, increased in the urine only when the S3 segment of the proximal tubule was damaged, as demonstrated by histological findings of the kidneys. HCBD caused early excretion of the enzyme related to the necrosis of the S3 segment, whereas potassium dichromate caused a slight increase only when the resulting lesion to this segment (vacuolization) began to develop. On the contrary, N-acetyl-beta-D-glucosaminidase activity showed the peak of excretion 24 and 34 h after treatment with HCBD or potassium dichromate, respectively, according to the histological findings of necrosis of the S3 segment (the former) and vacuolization of the S1-S2 segments (the latter). Excretion of total urinary proteins reached the peak 24 h (HCBD) and 48 h (potassium dichromate) after treatment. HCBD at 200 mg/kg body wt, caused a peak of glutamine synthetase activity in urine 10 h after injection, whereas the peak caused by doses of 50 and 100 mg/kg body wt. occurred 24 h following treatment. The peak of enzyme activity in urine significantly increased with the dose. The results suggest that the measurement of urinary activity of S3 segment-specific enzyme as glutamine synthetase allows us to detect early S3 segment-specific injury of the proximal tubule. In addition, the method for urinary enzyme activity appears sensitive, simple and fast.
在大鼠中研究了通过尿酶检测近端小管节段特异性损伤的可能性。在用100mg/kg体重的六氯-1:3-丁二烯（HCBD；腹腔注射）单次处理后，测定尿谷氨酰胺合成酶（一种仅定位于S3节段的酶）和N-乙酰-β-D-氨基葡萄糖苷酶（主要是S1-S2节段的酶，但S3节段也有），HCBD对S3节段有毒性，或用25mg/kg体重的重铬酸钾（皮下注射）单次处理后进行测定，重铬酸钾对S1-S2节段有毒性。还测量了总尿蛋白的排泄量。此外，确定了三种剂量（50、100和200mg/kg体重）的HCBD与尿中谷氨酰胺合成酶活性之间的剂量反应关系。根据为器官开发的方法的改进，采用一种新的尿测定法测量谷氨酰胺合成酶活性，只有当近端小管的S3节段受损时，尿中该酶活性才会增加，肾脏的组织学检查结果证明了这一点。HCBD导致与S3节段坏死相关的酶早期排泄，而重铬酸钾仅在该节段出现病变（空泡化）开始发展时才导致轻微增加。相反，根据S3节段坏死（前者）和S1-S2节段空泡化（后者）的组织学检查结果，N-乙酰-β-D-氨基葡萄糖苷酶活性分别在HCBD或重铬酸钾处理后24小时和34小时出现排泄高峰。处理后，总尿蛋白排泄量在24小时（HCBD）和48小时（重铬酸钾）达到峰值。200mg/kg体重的HCBD在注射后10小时导致尿中谷氨酰胺合成酶活性达到峰值，而50和100mg/kg体重剂量在处理后24小时出现峰值。尿中酶活性峰值随剂量显著增加。结果表明，测量尿中S3节段特异性酶谷氨酰胺合成酶的活性可以使我们检测到近端小管早期的S3节段特异性损伤。此外，尿酶活性测定方法显得灵敏、简单且快速。
