Lash L H, Jones D P
Mol Pharmacol. 1985 Sep;28(3):278-82.
Transport of the glutathione S-conjugate, S-(1,2-dichlorovinyl)glutathione (DCVG), was studied in renal basal-lateral membrane vesicles and isolated rat kidney cells. The time course of S-(1,2-dichlorovinyl)glutathione uptake in membrane vesicles exhibited an overshoot in the presence of sodium, indicating transport against a concentration gradient. The initial rate of uptake with membrane potential clamped at 0 mV was stimulated 2.5-fold by an inwardly directed gradient of 100 mM sodium chloride. Hyperpolarization of the membrane potential to -60 mV in the presence of sodium stimulated uptake another 2.7-fold, indicating that cotransport of sodium and S-(1,2-dichlorovinyl)glutathione is electrogenic. Sodium-dependent DCVG uptake was inhibited by glutathione, glutathione disulfide, and gamma-glutamylglutamate, but not by the corresponding cysteine S-conjugate, S-(1,2-dichlorovinyl)cysteine, indicating that the transport system is specific for the gamma-glutamyl moiety. Probenecid was also a potent inhibitor of sodium-dependent uptake. S-(1,2-dichlorovinyl)glutathione inhibited sodium-dependent uptake of glutathione in a concentration-dependent manner. Thus, these results show that uptake of DCVG and glutathione is mediated by the same sodium-coupled system. Uptake of S-(1,2-dichlorovinyl)glutathione was also demonstrated in isolated kidney cells; in the presence of sodium, cells accumulated approximately 4-fold more DCVG than in the absence of sodium. This basal-lateral membrane transport system can enable efficient delivery of circulating S-(1,2-dichlorovinyl)glutathione to kidney cells and may, therefore, contribute to its potent and selective nephrotoxicity. In addition, it suggests that renal clearance of glutathione conjugates may include transport from the blood through epithelial cells into the lumen as well as direct filtration through the glomerulus.
在肾基底外侧膜囊泡和分离的大鼠肾细胞中研究了谷胱甘肽S-共轭物S-(1,2-二氯乙烯基)谷胱甘肽(DCVG)的转运。膜囊泡中S-(1,2-二氯乙烯基)谷胱甘肽摄取的时间进程在有钠存在时呈现超调现象，表明是逆浓度梯度转运。当膜电位钳制在0 mV时，100 mM氯化钠的内向梯度使摄取的初始速率提高了2.5倍。在有钠存在的情况下，将膜电位超极化至-60 mV可使摄取再提高2.7倍，表明钠和S-(1,2-二氯乙烯基)谷胱甘肽的共转运是生电的。钠依赖性DCVG摄取受到谷胱甘肽、谷胱甘肽二硫化物和γ-谷氨酰谷氨酸的抑制，但不受相应的半胱氨酸S-共轭物S-(1,2-二氯乙烯基)半胱氨酸的抑制，表明转运系统对γ-谷氨酰部分具有特异性。丙磺舒也是钠依赖性摄取的有效抑制剂。S-(1,2-二氯乙烯基)谷胱甘肽以浓度依赖性方式抑制谷胱甘肽的钠依赖性摄取。因此，这些结果表明DCVG和谷胱甘肽的摄取是由相同的钠偶联系统介导的。在分离的肾细胞中也证实了S-(1,2-二氯乙烯基)谷胱甘肽的摄取；在有钠存在的情况下，细胞积累的DCVG比无钠时多约4倍。这种基底外侧膜转运系统能够使循环中的S-(1,2-二氯乙烯基)谷胱甘肽有效地递送至肾细胞，因此可能有助于其强大的选择性肾毒性。此外，这表明谷胱甘肽共轭物的肾清除可能包括从血液通过上皮细胞转运至管腔以及通过肾小球的直接滤过。
