The effect of inhibition of glutathione reductase on the detoxification of H2O2 by rabbit lens.
The effect of inhibition of glutathione reductase on the detoxification of H2O2 by rabbit lens.
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发表时间：
1983
影响因子：
4.4
通讯作者：
F. Giblin;J. McCready
中科院分区：
文献类型：
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作者：
F. Giblin;J. McCready
晶状体抵御H2O2的机制被认为包括谷胱甘肽（GSH）的代谢。在本研究中，使用蠕动泵将兔晶状体暴露于恒定浓度的H2O2（0.01至0.1 mM）培养基中。H2O2进入晶状体的速率与其在培养基中的浓度成正比，在0.1 mM H2O2条件下达到2.6 μ mol H2O2/lens/3 hr。高达0.06 mM H2O2，接近正常兔房水中H2O2的浓度，单磷酸己糖分流（HMPS）的活性线性增加，而晶态谷胱甘肽的浓度没有显著下降。然而，在0.1 mM H2O2下，HMPS活性急剧下降，GSH浓度同时下降，表明晶状体有氧化损伤的迹象。用谷胱甘肽还原酶（GR）抑制剂1,3-双（2-氯乙基）-1-亚硝基脲（BCNU）对晶体进行预处理，阻断了0.06 mM H2O2对HMPS活性的正常三倍刺激，导致氧化GSH的积累。这一结果表明H2O2不能与晶状体中的NADPH直接反应。BCNU不会影响HMPS对H2O2以外的化合物的反应，因为它不会改变亚甲基蓝对HMPS活性的刺激。该研究支持了房水中H2O2的解毒作用与晶状体中GSH代谢有关的假设，并表明GR活性受损的晶状体更容易受到过氧化氢的氧化损伤。
Mechanisms by which the lens protects against H2O2 are believed to include the metabolism of glutathione (GSH). In the present study, rabbit lenses were exposed to constant concentrations of H2O2 (0.01 to 0.1 mM) that were maintained in culture media with the use of a peristaltic pump. The rate at which H2O2 entered the lens was proportional to its concentration in the medium and reached 2.6 mumol H2O2/lens/3 hr at 0.1 mM H2O2. Up to 0.06 mM H2O2, a concentration that approximates that present in normal rabbit aqueous humor, the activity of the hexose monophosphate shunt (HMPS) increased linearly with no significant decrease in the concentration of lens GSH. However, at 0.1 mM H2O2, there was indication of oxidative damage to the lens as shown by a sharp decrease in HMPS activity and a coincident drop in the concentration of GSH. Pretreatment of lenses with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), an inhibitor of glutathione reductase (GR), blocked the normal threefold stimulation of HMPS activity occurring in the presence of 0.06 mM H2O2 and resulted in accumulation of oxidized GSH. This result demonstrated the inability of H2O2 to react directly with NADPH in the lens. BCNU was shown not to affect the potential of the HMPS to respond to compounds other than H2O2 since it did not alter methylene blue-stimulation of HMPS activity. The study supports the hypothesis that detoxification of H2O2 in the aqueous humor is linked to the metabolism of GSH in the lens and demonstrates that lenses with impaired GR activity are more susceptible to oxidative damage by peroxide.