Glutathione metabolism of human vascular endothelial cells under peroxidative stress

Glutathione (GSH) plays an important role in the cellular defense against (per-)oxidative stress. The capacity of this cellular defense system may be related to the oxygen tension, cells are normally subjected to in vivo; therefore, we studied the de novo synthesis of glutathione, and the redox turnover under peroxidative stress, in human umbilical vein and artery endothelial cells (HUVEC, HUAEC) and human skin fibroblasts. De novo synthesis in these cell types was studied in vitro by measuring the time course of intracellular GSH recovery after depletion with diamide. For fibroblasts, the initial rate of de novo synthesis after GSH depletion was twice that of the endothelial cell strains. In the endothelial cells (HUVEC, HUAEC) the original intracellular GSH level is reached within 40 min. while in the same time span, the GSH level in fibroblasts returned to 75% of control level. The activity of the hexose monophosphate shunt (HMS) was determined under oxidative stress as a measure for the coupled redox turnover of intracellular GSH. Under control conditions the HMS in endothelial cells was twice as high as in fibroblasts. Cumene hydroperoxide (40 microM) induced a three-fold increase in HMS in both HUVEC and HUAEC, while fibroblasts exhibited an increase of 83%. During the same peroxidative stress, the intracellular GSH concentration of HUVEC, HUAEC and fibroblasts stayed at control level. So with respect to GSH metabolism there were no differences between the two endothelial cell strains. In comparison with the endothelial cells, the fibroblasts were less susceptible toward oxidative stress.(ABSTRACT TRUNCATED AT 250 WORDS)