The Effect of tert-Butylhydroperoxide on the Thiol Redox Status in Human Erythrocytes and the Protective Role of Glucose and Antioxidants
For survival, living cells maintain their thiol redox status within acceptable limits by three different mechanisms: i. glutathione disulfide export, ii. reduction of glutathione disulfide by pentose phosphate pathway and, iii. reduction of glutathione disulfide by Protein-SH. To assess the relative contribution of each one of the systems, intracellular [glutathione], [glutathione disulfide] and their export, in fresh and aged erythrocytes subjected to oxidative stress, in \pm glucose and \pm antioxidants, were measured. Glutathione was rapidly oxidized by tert-butylhydroperoxide in \pm glucose in both groups. The regeneration of glutathione, in both groups, in \pm glucose was about 100 and 50%, respectively. In parallel, intracellular glutathione disulfide concentrations were increased by about 200-350%. The protective effects of ascorbate and a-tocopherol were similar and they behaved like radical scavengers. In the absence of glucose, glutathione regeneration depends solely on the reduction of glutathione disulfide by protein-SH, and so it remained at about 50%. In the presence of glucose, the pentose phophate pathway was also involved and the regeneration approached 100%. Since glutathione or glutathione export correspond from 0 to 1% of total cellular glutathione content, glutathione export makes no contribution to the establishment of the intracellular thiol redox status.
Human erythrocytes, GSH, GSSG, Thiol redox status, tert}-Butylhydroperoxide, Ascorbate, a-Tocopherol.