Leszczyńska A, Pfaff E
Biochem Pharmacol. 1982 May 15;31(10):1911-8. doi: 10.1016/0006-2952(82)90497-x.
The uptake of methotrexate (MTX) by isolated rat hepatocytes and its changes under the influence of exogenous GSH have been studied under various conditions: GSH concentration, pH of incubation medium, preincubation of cells prior to MTX and GSH addition, ionic composition of the incubation medium (standard saline, Na+-free, Na+ and K+-free, or ion-deficient), after prior treatment of cells by membrane -SH blockers (p-CMBS, 4-CMB and DIP2+) and ATP. It was found that GSH strongly accelerated MTX uptake. This effect depended on GSH concentration and on preincubation of cells. The GSH effect was not dependent on medium pH in spite of an observed close relationship between pH of incubate and MTX transport itself. Activation by GSH of MTX transport was connected to an increase in intracellular K+. It was also noted that while blockers of membrane -SH groups like p-CMBS and 4-CMB inhibited MTX uptake and increased the intracellular Na+/K+ ratio, both effects were partially overcome by GSH. After treatment by DIP2+, Na+/K+ ratio was unaffected, but MTX uptake inhibited. Still GSH abolished inhibition. Added ATP also inhibited MTX uptake and caused loss of cellular K+ and accumulation of Na+. Here neither effect could be reversed by GSH; consequently, high cellular amounts of K+ and MTX accumulated by previous action of GSH were depleted on subsequent ATP addition. MTX uptake was low in sucrose medium. But in this ion-deficient medium, GSH had the greatest stimulatory effect on MTX uptake. It is concluded that binding GSH can affect the redox state of the -S-S-/-SH groups of the cellular plasma membrane and that this effect of GSH might demonstrate involvement of the redox state in the control of MTX permeability.
研究了在多种条件下，分离的大鼠肝细胞对甲氨蝶呤（MTX）的摄取及其在外源谷胱甘肽（GSH）影响下的变化：GSH浓度、孵育介质的pH值、在添加MTX和GSH之前对细胞进行预孵育、孵育介质的离子组成（标准盐水、无钠、无钠和钾、或离子缺乏）、在细胞先用膜-SH阻断剂（对氯汞苯甲酸、4-氯汞苯甲酸和二异丙基氟磷酸）和ATP处理之后。发现GSH强烈加速MTX的摄取。这种作用取决于GSH浓度和细胞的预孵育。尽管观察到孵育pH值与MTX转运本身之间存在密切关系，但GSH的作用并不依赖于介质pH值。GSH对MTX转运的激活与细胞内钾离子增加有关。还注意到，像对氯汞苯甲酸和4-氯汞苯甲酸这样的膜-SH基团阻断剂抑制MTX摄取并增加细胞内钠/钾比率，但这两种作用都被GSH部分克服。在用二异丙基氟磷酸处理后，钠/钾比率未受影响，但MTX摄取受到抑制。不过GSH消除了这种抑制。添加ATP也抑制MTX摄取，并导致细胞钾离子丢失和钠离子积累。在这里，GSH无法逆转任何一种作用；因此，先前GSH作用积累的高细胞量的钾离子和MTX在随后添加ATP时被耗尽。MTX在蔗糖介质中的摄取较低。但在这种离子缺乏的介质中，GSH对MTX摄取具有最大的刺激作用。得出的结论是，结合的GSH可以影响细胞质膜-S-S-/-SH基团的氧化还原状态，并且GSH的这种作用可能表明氧化还原状态参与了对MTX通透性的控制。
