INFLUENCE OF OXYGEN RADICALS GENERATING AGENTS ON EICOSANOID METABOLISM OF HUMAN ENDOTHELIAL-CELLS

Human umbilical venous endothelial cells were incubated with increasing concentrations (0.001-10 mmol/l) of H2O2 or cumene hydroperoxide. PGI2 was released within the first five minutes, whereas a significant increase in TXA2-release was not observed before 10 minutes after stimulation. Furthermore the content of intracellular ATP and the level of cytosolic free Ca2+ were measured. Doses of 0.01 mmol/l H2O2 or cumene hydroperoxide increased the intracellular ATP-level. Doses higher than 0.1 mmol/l led to a decrease of ATP. The cytosolic free calcium (Ca2+) increased on stimulating the cells with 0.1 mmol/l cumene hydroperoxide between 120 and 240 seconds after stimulation, whereas 0.1 mmol/l H2O2 had no effects. These data give strong evidence, that eicosanoid-synthesis is directly started by oxygen radicals, followed by an elevation of intracellular free Ca2+.