Toxicity induced by cumene hydroperoxide in leech Retzius nerve cells: the protective role of glutathione.

In the present study, we studied the ability of glutathione (GSH) to detoxify exogenously applied cumene hydroperoxide (CHP). Exposure of leech Retzius nerve cells to CHP (1.5 mM) induced a marked prolongation of the spontaneous spike potential of these cells. Early after depolarization, and a cardiac-like action potential with a rapid depolarization followed by a sustained depolarization or plateau, which is terminated by a rapid repolarization were recorded. GSH (0.2 mM) significantly inhibited the effects of CHP on the duration of the action potential and suppressed CHP-induced spontaneous repetitive activity. Voltage-clamp recordings showed that CHP (1.5 mM) caused significant changes in the outward potassium currents. The fast and slow steady part of the potassium outward current was reduced by 46% and 39%, respectively. GSH applied in a concentration of 0.2 mM partially blocked the effect of CHP on the calcium-activated potassium currents. The fast and slow calcium-activated potassium currents were suppressed by about 20% and 15%, respectively. These results suggest that the neurotoxic effect of CHP on spontaneous spike electrogenesis and calcium-activated potassium currents of leech Retzius nerve cells was reduced in the presence of GSH.