Cammarata P R, Tse D, Yorio T
Department of Anatomy and Cell Biology, Texas College of Osteopathic Medicine/University of North Texas, Forth Worth.
Curr Eye Res. 1991 Apr;10(4):321-30. doi: 10.3109/02713689108996338.
Exposure of cultured bovine lens epithelial cells (BLECs) to minimal essential medium (MEM) containing 40 mM galactose (Gal) promotes a decrease in the cellular content of reduced glutathione (GSH) as galactitol increases. Incubation of BLECs with Gal also leads to a reduction in 3H-myo-inositol (3H-MI) concentrating capability. Studies were therefore initiated to determine the nature of the relationship between polyol accumulation, GSH content and the attenuation of the active transport of myo-inositol. The inhibitor of glutathione biosynthesis, L-buthionine sulfoximine (L-BSO) was used in order to lower the intracellular pool of GSH in MEM-maintained cells to a concentration below that characteristically observed in Gal-treated cells, under conditions whereby no galactitol accumulation could or had occurred. L-BSO (0.5 mM) was simultaneously administered to BLECs maintained in either MEM or Gal for up to five days. The cellular content of GSH after five days of continuous incubation was 3.3 micrograms GSH/micrograms PO4 in MEM alone and 0.45 microgram GSH/microgram PO4 in MEM + BSO. Moreover, the GSH content in BLECs exposed to Gal for five days was 1.9 micrograms GSH/micrograms PO4 and was not detectable in the Gal + BSO-treated cells. However, the ability to concentrate 3H-MI in MEM + BSO-treated BLECs was equivalent to that observed with MEM-maintained cells regardless of the significant difference in GSH content. Likewise, L-BSO addition to Gal-treated cells, while virtually depleting the intracellular GSH content, did not further decrease the ability of the cells to accumulate 3H-MI compared to that observed with BLECs in Gal alone. Indeed, supplementation of Gal-treated cells with exogenous GSH failed to correct the Gal-induced attenuation in myo-inositol concentrating ability. These studies demonstrate that the Gal-induced depletion of cellular GSH and the Gal-induced deficit in ability to concentrate myo-inositol are not associated and represent independent events. That is, depletion of lens cell GSH does not lead to the attenuation of myo-inositol uptake in cultured lens epithelial cells.
将培养的牛晶状体上皮细胞（BLECs）暴露于含有40 mM半乳糖（Gal）的最低必需培养基（MEM）中，随着半乳糖醇增加，细胞内还原型谷胱甘肽（GSH）含量会降低。用Gal孵育BLECs也会导致3H-肌醇（3H-MI）浓缩能力下降。因此开展了研究，以确定多元醇积累、GSH含量与肌醇主动转运减弱之间关系的本质。使用谷胱甘肽生物合成抑制剂L-丁硫氨酸亚砜胺（L-BSO），以便在没有半乳糖醇积累或已发生半乳糖醇积累的条件下，将MEM维持的细胞内GSH池浓度降低至低于Gal处理细胞中通常观察到的浓度。将L-BSO（0.5 mM）同时给予维持在MEM或Gal中的BLECs，持续长达五天。连续孵育五天后，仅在MEM中细胞内GSH含量为3.3微克GSH/微克PO4，在MEM + BSO中为0.45微克GSH/微克PO4。此外，暴露于Gal五天的BLECs中GSH含量为1.9微克GSH/微克PO4，在Gal + BSO处理的细胞中无法检测到。然而，无论GSH含量存在显著差异，MEM + BSO处理的BLECs中浓缩3H-MI的能力与MEM维持的细胞中观察到的能力相当。同样，向Gal处理的细胞中添加L-BSO，虽然实际上耗尽了细胞内GSH含量，但与仅在Gal中的BLECs相比，并没有进一步降低细胞积累3H-MI的能力。事实上，用外源性GSH补充Gal处理过的细胞未能纠正Gal诱导的肌醇浓缩能力减弱。这些研究表明，Gal诱导的细胞GSH耗竭和Gal诱导的肌醇浓缩能力缺陷并无关联，是独立的事件。也就是说，晶状体细胞GSH的耗竭不会导致培养的晶状体上皮细胞中肌醇摄取的减弱。
