Effect of chronic hydrogen peroxide exposure on neuronal electric membrane properties

In view of the well known cytotoxic effects of hydrogen peroxide, it was decided to investigate the neurotoxic effects of this oxygen metabolite on the electric membrane properties of neurons. Neural cell cultures of adult mouse dorsal root ganglia were chronically exposed to H2O2 and electrical properties of the neurons determined using intracellular recordings. Chronic H2O2 exposure caused a variety of alterations in EMP including increased overshoot, afterhyperpolarization and duration of the action potential. The prolongation of the action potential was due to a shift to a more biphasic type of repolarization and to a decreased rate of fall of the initial phase of repolarization. The observed pattern of EMP alterations in conjunction with previous investigation of ionic dependence in these neurons suggested that hydrogen peroxide may exert its toxic effect, at least in part, by increasing the calcium dependence of the action potential ionic mechanism.