LIPID-PEROXIDATION, ANTIOXIDATIVE ENZYME-ACTIVITIES, AND CYTOSOLIC-FREE CALCIUM LEVELS IN RAT HIPPOCAMPUS-DERIVED CELLS EXPOSED TO FREE-RADICALS

To elucidate mechanisms of free radical-induced neuronal cell death, l ipid peroxidation measured as thiobarbituric acid-reactive substances (TBARS), three antioxidative enzyme activities (superoxide dismutase, glutathione peroxidase, and catalse), and cytosolic free Ca2+ (Ca(2+)i ) were examined in rat hippocampus-derived cells (HV16-4) exposed to f ree radicals generated by a hypoxanthine-xanthine oxidase system. The viability of cells decreased with an increase in numbers of free radic al positive cells in a dose-dependent manner of xanthine oxidase. The protein-bound TBARS did not change, whereas free TBARS increased at 13 5% of initial value. No remarkable change was observed in three antiox idative enzyme activities. On the other hand, Ca(2+)i increased after exposure followed by cell death. Furthermore, the addition of Co2+, a nonspecific Ca2+ channel blocker, delayed the increase of Ca(2+)i and subsequent cell death. These findings suggested that the influx of Ca2 + played a crucial role for HV16-4 cell death induced by free radicals .