EXPOSURE TO LOW CONCENTRATIONS OF HYDROGEN-PEROXIDE CAUSES DELAYED ENDOTHELIAL-CELL DEATH AND INHIBITS PROLIFERATION OF SURVIVING CELLS

Cultured bovine aortic endothelial cells were briefly exposed to low concentrations of hydrogen peroxide (0.005 to 0.05 mmol/l). At these concentrations cells do not suffer immediate lysis, but a high proportion underwent delayed cell death over the next 24 h, with changes in nuclear morphology, the appearance of nucleosomal fragments in extracted nuclear DNA, and the appearance of numerous DNA strand breaks demonstrated by 3'OH in situ end-labelling compatible with apoptotic cell death. At the same time, there was marked inhibition of [H-3]thymidine uptake, and inhibition of the incorporation of the thymidine analogue 5-bromo-2'deoxy-uridine into nuclear DNA. Cells which survived apoptosis showed inhibition of cell division on subsequent culture for up to 15 days, and there were striking morphological changes, with the formation of uninucleate or multinucleate giant cells. These effects may be relevant to the mechanisms by which brief exposure to oxidative stress causes progressive vessel wall damage.