Voltage-activated calcium channel currents of rat dorsal root ganglion cells are reduced by trimethyl lead

Using the conventional whole-cell patch-clamp recording technique with cultured neurones of rat dorsal root ganglions (DRG), we analysed the effects of trimethyl lead (TML) on voltage-activated calcium channel currents. TML reduces voltage-activated calcium channel currents in a dose-dependent manner, with a threshold concentration below 0.5 mu M and a total reduction of the current (greater than or equal to 80% of the control current) at concentrations above 50 mu M. Half of the current is abolished at TML concentrations between 1 and 5 mu M. The action is irreversible and is not voltage dependent. After application of TML the current decreases with each activation of the channel until a steady state is reached after 8-12 min, when the channel was activated every 10 s. The channel had to be in the open state for TML to act. TML is a potent compound for reducing voltage activated calcium channel currents. These effects of TML must be taken into account in explaining the neurotoxic effects of this organic metal compound. (C) 1997 Elsevier Science Ireland Ltd.