Lipid peroxidation and lysosomal enzyme release induced by vanadate in vitro.

Incubation of premitochondrial liver homogenate supernatants of phenobarbital-induced rats with sodium vanadate led to a time- and concentration-dependent formation of malondialdehyde and a parallel release of beta-glucuronidase from lysosomes. Both were inhibited in the presence of glutathione, (+)-catechin or dithiocarb, and took place after a lag phase of 30 min. In contrast, the glutathione content dropped immediately after addition of vanadate. Scavengers of reactive oxygen species had no effect on vanadate-induced lipid peroxidation. In liver homogenates of non-induced rats vanadate-promoted lipid peroxidation was 7.3 times lower than in those of phenobarbital-induced animals, suggesting the involvement of the microsomal mixed-function oxidase system. Thus, vanadate seems to act as a pro-oxidant of the enzymatically-promoted lipid peroxidation.