Role of renal cysteine conjugate beta-lyase in the mechanism of compound A nephrotoxicity in rats
Role of renal cysteine conjugate beta-lyase in the mechanism of compound A nephrotoxicity in rats
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DOI：
10.1097/00000542-199701000-00020
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发表时间：
1997-01-01
期刊：
影响因子：
8.8
通讯作者：
Kilty, GC
中科院分区：
文献类型：
--
作者：
Kharasch, ED;Thorning, D;Kilty, GC
背景：七氟醚降解产物化合物A在大鼠中具有肾毒性，在大鼠中它被广泛代谢为谷胱甘肽和半胱氨酸s缀合物。化合物A对大鼠肾毒性的作用机制尚不清楚。化合物A的肾毒性尚未在人体中观察到。作者验证了化合物A s缀合物的肾脏摄取和肾脏半胱氨酸缀合物β -裂解酶的代谢介导大鼠化合物A肾毒性的假设。方法：将化合物A（初始剂量反应实验0 ~ 0.3 mmol/kg，后续抑制剂实验0.2 mmol/kg）腹腔注射Fischer 344大鼠。抑制剂实验分为3组：抑制剂（对照组）、化合物A、抑制剂加化合物A。抑制剂为肾有机阴离子转运和s -缀合物摄取抑制剂probenecid （0.5 mmol/kg， 10 h后重复）；Acivicin (10 mg/kg和10 h后5 mg/kg)，一种γ -谷氨酰转移酶抑制剂，一种将谷胱甘肽偶联物切割成半胱氨酸偶联物的酶；取肾半胱氨酸偶联β -水解酶抑制剂氨基乙酸（0.5 mmol/kg和10 h后0.25 mmol/kg），取尿24 h后处死，采用光镜检查和生化指标（血清尿素氮和肌酐浓度、尿量、尿中蛋白质、葡萄糖和α -谷胱甘肽- s -转移酶（α - GST）的排泄量）评估肾毒性。结果：化合物A引起剂量相关的肾毒性，表现为皮质-髓交界处选择性近端小管细胞坏死、利尿、蛋白尿、血糖升高和α - GST排泄增加。Probenecid预处理显著（P < 0.05）降低了化合物a诱导的尿中蛋白质（45.5 +/- 3.8 mg/24 h vs. 25.9 +/- 1.7 mg/24 h）、葡萄糖（28.8 +/- 6.2 mg/24 h vs. 10.9 +/- 3.2 mg/24 h）和α - GST （6.3 +/- 0.8 mu g/24 h vs. 1.0 +/- 0.2 mu g/24 h）排泄量的增加（平均+/- SE），并完全阻止近端小管细胞坏死。氨基乙酸预处理显著降低了化合物a诱导的尿量（19.7 +/- 3.5 ml/24 h vs. 9.8 +/- 0.8 ml/24 h）、蛋白质排泄（37.2 +/- 2.7 mg/24 h vs. 22.2 +/- 1.8 mg/24 h）和α - GST排泄（5.8 +/- 1.5 vs. 2.3 μ g/24 h +/- 0.8 μ g/24 h）的增加，但未显著改变损伤的组织学模式，相反，acivicin预处理增加了化合物a诱导的损伤的组织学和生化指标。化合物A相关的尿氟排泄量增加，反映了化合物A的代谢，并没有被任何抑制剂治疗实质性地改变。结论：腹腔注射化合物A提供了一个令人满意的肾毒性模型，氨基乙酸和probenecid显著降低了化合物A肾毒性的组织学和生化证据，而acivicin则增强了毒性。这些结果表明，复方A-谷胱甘肽或复方A-半胱氨酸缀合物的肾脏摄取和肾β -水解酶对半胱氨酸缀合物的代谢在一定程度上介导了大鼠复方A的肾毒性。
Background: The sevoflurane degradation product compound A is nephrotoxic in rats, in which it undergoes extensive metabolism to glutathione and cysteine S-conjugates. The mechanism of compound A nephrotoxicity in rats is unknown. Compound A nephrotoxicity has not been observed in humans. The authors tested the hypothesis that renal uptake of compound A S-conjugates and metabolism by renal cysteine conjugate beta-lyase mediate compound A nephrotoxicity in rats.Methods: Compound A (0-0.3 mmol/kg in initial dose-response experiments and 0.2 mmol/kg in subsequent inhibitor experiments) was administered to Fischer 344 rats by intraperitoneal injection. Inhibitor experiments consisted of three groups: inhibitor (control), compound A, or inhibitor plus compound A. The inhibitors were probenecid (0.5 mmol/kg, repeated 10 h later), an inhibitor of renal organic anion transport and S-conjugate uptake; acivicin (10 mg/kg and 5 mg/kg 10 h later), an inhibitor of gamma-glutamyl transferase, an enzyme that cleaves glutathione conjugates to cysteine conjugates; and aminooxyacetic acid (0.5 mmol/kg and 0.25 mmol/kg 10 h later), an inhibitor of renal cysteine conjugate beta-lyase, Urine was collected for 24 h and then the animals were killed, Nephrotoxicity was assessed by light microscopic examination and biochemical markers (serum urea nitrogen and creatinine concentration, urine volume and urine excretion of protein, glucose, and alpha-glutathione-S-transferase [(alpha GST], a marker of tubular necrosis).Results: Compound A caused dose-related nephrotoxicity, as shown by selective proximal tubular cell necrosis at the corticomedullary junction, diuresis, proteinuria, glucosuria, and increased alpha GST excretion. Probenecid pretreatment significantly (P < 0.05) diminished compound A-induced increases (mean +/- SE) in urine excretion of protein (45.5 +/- 3.8 mg/24 h vs. 25.9 +/- 1.7 mg/24 h), glucose (28.8 +/- 6.2 mg/24 h vs. 10.9 +/- 3.2 mg/24 h), and alpha GST (6.3 +/- 0.8 mu g/24 h vs. 1.0 +/- 0.2 mu g/24 h) and completely prevented proximal tubular cell necrosis, Aminooxyacetic acid pretreatment significantly diminished compound A-induced increases in urine volume (19.7 +/- 3.5 ml/24 h vs. 9.8 +/- 0.8 ml/24 h), protein excretion (37.2 +/- 2.7 mg/24 h vs. 22.2 +/- 1.8 mg/24 h), and alpha GST excretion (5.8 +/- 1.5 vs. 2.3 mu g/24 h +/- 0.8 mu g/24 h) but did not significantly alter the histologic pattern of injury, In contrast, acivicin pretreatment increased the compound A-induced histologic and biochemical markers of injury. Compound A-related increases in urine fluoride excretion, reflecting compound A metabolism, were not substantially altered by any of the inhibitor treatments,Conclusions: Intraperitoneal compound A administration provides a satisfactory model of nephrotoxicity, Aminooxyacetic acid and probenecid significantly diminished histologic and biochemical evidence of compound A nephrotoxicity, whereas acivicin potentiated toxicity. These results suggest that renal uptake of compound A-glutathione or compound A-cysteine conjugates and cysteine conjugates metabolism by renal beta-lyase mediate, in part, compound A nephrotoxicity in rats.