Effect of endothelin-1 on intracellular glutathione and lipid peroxide availability and on the secretion of vasoactive substances by human umbilical vein endothelial cells.

Abstract

The major pathophysiologic changes observed in preeclampsia suggest that endothelial cell dysfunction plays an important role in this disorder. The pathway mediating endothelial cell layer dysfunction is unknown. The concentration of endothelin-1 (ET-1), a potent mammalian vasoconstrictor peptide produced by the vascular endothelium, has been observed to be significantly increased in preeclampsia. In this study, we determined the in vitro effect of endothelin-1 on glutathione and lipid peroxide levels and on the secretion of vasoactive substances by human umbilical vein endothelial cells (HUVECs). Human umbilical vein endothelial cells were incubated for 24 h in the presence of different concentrations of ET-1 (0-1000 pmol L(-1)), which were shown in an earlier experiment to have no effects on vitality and proliferation rate of HUVECs. The levels of glutathione (GSH) and lipid peroxides (LPO) were measured in endothelial cell lysates. For the measurement of vasoactive substances, levels of nitric oxide (NO), prostacyclin (PGI2) and thromboxane A2 (TXA2) were measured in endothelial cell supernatants. At lower concentrations (5-50 pmol L(-1)), ET-1 increases the intracellular content of LPO, stimulates the secretion of TXA2, but inhibits the secretion of PGI2 in endothelial cells compared with control cells. At higher concentrations (100-1000 pmol L(-1)), ET-1 increases the intracellular content of GSH, but results in a decrease of LPO, and increase of PGI2, back to control levels. ET-1 has no effect on NO secretion. These findings demonstrate that at concentrations corresponding to values in plasma from preeclamptic women, ET-1 induces oxidative stress and results in altered secretion of vasoactive substances in human endothelial cells. We conclude that ET-1 may participate in the pathway leading to endothelial cell dysfunction seen in preeclampsia.