involvement of cytochrome p-450 in n-butyl nitrite-induced hepatocyte cytotoxicity

addition of n-butyl nitrite to isolated rat hepatocytes caused an immediate glutathione depletion followed by an inhibition of mitochondrial respiration, inhi- bition of glycolysis and atp depletion. at cytotoxic butyl nitrite concentrations, lipid  peroxidation  occurred  before  the  plasma  membrane  was  disrupted. cytochrome p-450 inhibitors inhibited peroxynitrite formation and prevented butyl nitrite-induced mitochondrial respiration inhibition, atp depletion, lipid peroxidation and plasma membrane disruption. however, glutathione depletion, s-nitroso-glutathione (gsno) formation, or the inhibition of glycolysis was not affected by cytochrome p-450 inhibitors. glutathione-depleted hepatocytes were resistant to butyl nitrite which suggests that cytotoxicity and peroxynitrite forma- tion results from gsno formation. peroxynitrite formation was also inhibited by reactive oxygen scavengers. these findings suggest that cytochrome p-450 iso- forms (particularly cyp2e1) act as a source of superoxide anion radicals in the formation of cytotoxic peroxynitrite from nitric oxide.