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pubmed:abstractText |
We studied the relationship between the site of production of oxygen radicals and their effect on a rat thymocyte functional activity, the glucose transport, measured using a radioactive analogue of glucose, 2-deoxy-glucose. We compared the effects of a hydrophilic thermolabile azo compound, mimicking a radical attack outside the cell, with the lipid-soluble cumene hydroperoxide, which initiates lipid peroxidation in cell membranes. Our results show that a low grade oxidative stress stimulated glucose uptake rapidly, independently of the site of radical generation. In the presence of the azocompound, glucose uptake increased smoothly, attaining its maximum extent within 1 h. In thymocytes treated with cumene hydroperoxide the rate of glucose transport increased suddenly and remained constant over 1 h. The effects of the radical donors on TBARS production and protein sulfhydryl groups content were also evaluated. In thymocytes treated with the azo derivative no lipid peroxidation was observed, but a slow decrease of protein thiol groups occurred; after the addition of cumene hydroperoxide sulfhydryl groups did not change and TBARS increased significantly. The water-soluble antioxidant Trolox was able to remove the glucose uptake increase induced by the hydrophilic initiator and to delay the loss of membrane integrity.
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