Suzuki C A, Cherian M G
Department of Pharmacology and Toxicology, University of Western Ontario, London, Canada.
Toxicology. 1990 Nov;64(2):113-27. doi: 10.1016/0300-483x(90)90129-5.
The involvement of metallothionein (MT) in the nephrotoxicity of cis-diamminedichloroplatinum (c-DDP) was investigated in rats using enzyme excretion and histology as indicators of renal damage. In addition, the effects of renal glutathione (GSH) depletion on the nephrotoxicity of c-DDP was assessed by organic anion transport in renal cortical slices. A dose of 6.0 mg c-DDP/kg body wt, i.p. was administered to rats either as a single injection of 6.0 mg/kg or as six daily injections of 1.0 mg/kg. Concentrations of platinum (Pt) after c-DDP injection in both dosing regimens were approximately 12 micrograms/g in kidney and 2 micrograms/g in liver. However, there were no increases in either hepatic or renal concentrations of MT after both series of c-DDP injections. Fractionation of kidney cytosols from c-DDP injected rats on Sephadex G-75 columns revealed that 60-70% of cytosolic Pt was associated with proteins of high molecular weight and 15-20% of the Pt associated with the low molecular weight ligands. No discernable Pt peak was detected in the elution volume of MT. Pretreatment of rats with ZnSO4 increased both hepatic and renal concentrations of MT, but there was no Pt associated with the MT fraction after a subsequent injection of c-DDP. Small increases in the urinary excretion of the lysosomal enzyme, N-acetyl-beta-D-glucosaminidase and two brush border enzymes, alkaline phosphatase and gamma-glutamyltranspeptidase were observed 2 and 3 days after a single injection of c-DDP (6.0 mg/kg body wt, i.p.). Urinary creatinine excretion decreased by 50% 1 day after c-DDP injection and continued to decrease for the next 2 days. On the third day after c-DDP treatment, a small but significant decrease in body weight was also observed in the c-DDP injected animals. Pretreatment with Zn did not alter the c-DDP-induced enzymuria or renal tubular damage but slightly attenuated both the decrease in creatinine excretion and the loss in body weight. Uptake of the organic anion, p-aminohippuric acid (PAH) was reduced at 12 and 24 h after c-DDP injection. Reduction of tissue GSH concentrations by pretreatment with buthionine sulfoxime (BSO), resulted in only a slight increase in the c-DDP-induced inhibition of PAH uptake at 24 h after c-DDP injection. These results suggest that, in rats, neither MT nor GSH appear to play major roles in the binding or nephrotoxicity of c-DDP.
以酶排泄和组织学作为肾损伤指标，在大鼠中研究了金属硫蛋白（MT）在顺二氨二氯铂（c-DDP）肾毒性中的作用。此外，通过肾皮质切片中的有机阴离子转运评估了肾谷胱甘肽（GSH）耗竭对c-DDP肾毒性的影响。以6.0 mg c-DDP/kg体重的剂量腹腔注射给大鼠，给药方式为单次注射6.0 mg/kg或每日注射6次，每次1.0 mg/kg。两种给药方案注射c-DDP后，肾脏中铂（Pt）的浓度约为12微克/克，肝脏中为2微克/克。然而，在这两组c-DDP注射后，肝脏和肾脏中MT的浓度均未增加。对注射c-DDP的大鼠的肾脏胞质溶胶在葡聚糖凝胶G-75柱上进行分级分离，结果显示60-70%的胞质溶胶Pt与高分子量蛋白质结合，15-20%的Pt与低分子量配体结合。在MT的洗脱体积中未检测到可分辨的Pt峰。用硫酸锌预处理大鼠可增加肝脏和肾脏中MT的浓度，但在随后注射c-DDP后，MT部分未检测到与Pt结合。单次注射c-DDP（6.0 mg/kg体重，腹腔注射）后2天和3天，溶酶体酶N-乙酰-β-D-氨基葡萄糖苷酶以及两种刷状缘酶碱性磷酸酶和γ-谷氨酰转肽酶的尿排泄量略有增加。c-DDP注射后1天，尿肌酐排泄量减少50%，并在接下来的2天持续下降。在c-DDP治疗后的第三天，注射c-DDP的动物体重也出现了轻微但显著的下降。锌预处理并未改变c-DDP诱导的酶尿或肾小管损伤，但略微减轻了肌酐排泄量的下降和体重的减轻。c-DDP注射后12小时和24小时，有机阴离子对氨基马尿酸（PAH）的摄取减少。用丁硫氨酸亚砜胺（BSO）预处理降低组织GSH浓度，仅导致c-DDP注射后24小时PAH摄取受抑制的轻微增加。这些结果表明，在大鼠中，MT和GSH似乎在c-DDP的结合或肾毒性中均未起主要作用。
