Metabolism and toxicity of trichloroethylene and S-(1,2-dichlorovinyl)-L-cysteine in freshly isolated human proximal tubular cells
Metabolism and toxicity of trichloroethylene and S-(1,2-dichlorovinyl)-L-cysteine in freshly isolated human proximal tubular cells
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DOI：
10.1093/toxsci/53.2.458
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发表时间：
2000-02-01
影响因子：
3.8
通讯作者：
Lash, LH
中科院分区：
文献类型：
--
作者：
Cummings, BS;Lash, LH
三氯乙烯（三）引起适度的细胞毒性，在新鲜分离的人近端肾小管（hPT）细胞，乳酸脱氢酶（LDH）活性显着降低后1小时暴露于500 μ M三评估。Tri通过细胞色素P-450氧化代谢形成水合氯醛（CH）仅在四名受试患者中的一名患者的肾微粒体中检测到，在hPT细胞中未检测到。相比之下，在来自每个测试患者的细胞中检测到Tri的GSH缀合。Tri代谢为GSH结合物S-（1，2-二氯乙烯基）谷胱甘肽（DCVG）的动力学遵循双相动力学，表观Km和V-max值分别为0.51和24.9 mM以及0.10和1.0 nmol/min/mg蛋白。S-（1，2-二氯乙烯基）-L-半胱氨酸（DCVC）是Tri的半胱氨酸共轭代谢物，被认为是倒数第二个肾毒性物质，在新鲜分离的hPT细胞中引起LDH释放的时间和浓度依赖性增加。用0.1 mM氨氧乙酸预孵育hPT细胞不能保护hPT细胞免受DCVC诱导的细胞损伤，这表明除了半胱氨酸缀合物β-裂解酶之外的另一种酶在DCVC生物活化中可能是重要的。这项研究是第一次测量Tri和DCVC在新鲜分离的人肾细胞中的细胞毒性和代谢。这些数据表明，参与hPT细胞中Tri的细胞毒性和代谢的途径是GSH缀合途径，并且细胞色素P-450依赖性途径在人体肾脏Tri代谢中几乎没有直接作用。
Trichloroethylene (Tri) caused modest cytotoxicity in freshly isolated human proximal tubular (hPT) cells, as assessed by significant decreases in lactate dehydrogenase (LDH) activity after 1 h of exposure to 500 mu M Tri. Oxidative metabolism of Tri by cytochrome P-450 to form chloral hydrate (CH) was only detectable in kidney microsomes from one patient out of four tested and was not detected in hPT cells. In contrast, GSH conjugation of Tri was detected in cells from every patient tested. The kinetics of Tri metabolism to its GSH conjugate S-(1,2-dichlorovinyl)glutathione (DCVG) followed biphasic kinetics, with apparent K-m and V-max values of 0.51 and 24.9 mM and 0.10 and 1.0 nmol/min per mg protein, respectively. S-(1,2-dichlorovinyl)-L-cysteine (DCVC), the cysteine conjugate metabolite of Tri that is considered the penultimate nephrotoxic species, caused both time- and concentration-dependent increases in LDH release in freshly isolated hPT cells. Preincubation of hPT cells with 0.1 mM aminooxyacetic acid did not protect hPT cells from DCVC-induced cellular injury, suggesting that another enzyme besides the cysteine conjugate beta-lyase may be important in DCVC bioactivation. This study is the first to measure the cytotoxicity and metabolism of Tri and DCVC in freshly isolated cells from the human kidney. These data indicate that the pathway involved in the cytotoxicity and metabolism of Tri in hPT cells is the GSH conjugation pathway and that the cytochrome P-450-dependent pathway has little direct role in renal Tri metabolism in humans.