The increase of cytosolic free calcium in human umbilical vein endothe
lial cells caused by peroxides was used as a model to determine and co
mpare the putative cytoprotective properties of substances known to in
terfere with the generation or metabolism of reactive oxygen species.
Hydrophilic hydrogen peroxide and lipophilic cumene hydroperoxide were
used as sources of reactive oxygen. [Ca2+](i) in endothelial cells wa
s measured by the FURA method and the resting level was found to be 12
9.3 +/- 14.1 nM. Both peroxides were found to increase cytosolic calci
um with dependence on the concentration and on the presence of extrace
llular calcium. Among the substances tested, only catalase and N-acety
l-cysteine were able to exhibit a significant cytoprotective effect.