Involvement of extracellular ascorbate and iron in hydroxyl radical generation in rat striatum in carbon monoxide poisoning.

Carbon monoxide (CO) poisoning stimulated generation in rat striatum of toxic hydroxyl radicals (*OH), which might participate in the CO-induced neuronal injury. Since an increase in extracellular ascorbate (AA) stimulated *OH generation in the presence of endogenous metals, including iron, in rat striatum in vivo, we examined the role of extracellular AA in *OH generation due to CO poisoning in the present study. The CO-induced *OH generation in the striatum was strongly suppressed by intrastriatal administration of active, but not inactivated, AA oxidase, which degrades extracellular AA. In addition, CO poisoning caused a significant increase in extracellular AA in rat striatum, suggesting a role of extracellular AA in the CO-induced *OH generation. However, the time-course of changes in extracellular AA could not be completely superimposed on that of the CO-induced *OH generation. On the other hand, the CO-induced *OH generation was completely suppressed by an iron chelator, deferoxamine. These findings suggest that *OH generation in rat striatum due to CO poisoning may involve both extracellular AA and chelatable iron.