Inhibitory effect of tungsten carbide nanoparticles on voltage-gated potassium currents of hippocampal CA1 neurons

The effects of tungsten carbide nanoparticles (nano-WC) on the properties of voltage-dependent potassium currents and evoked action potentials were studied in the hippocampal CA1 pyramidal neurons of rats at the ages of postnatal days 10-14 using the whole-cell patch-clamp technique. The results indicated that: (1) the amplitudes of transient outward potassium current (I A) and delayed rectifier potassium current (I K) were significantly decreased by 10 -7g/ml nano-WC, while the current-voltage curves of I A and I K were significantly decreased by nano-WC from +10 to +90mV. (2) Nano-WC produced a depolarizing shift in the steady-state activation curve of I A and I K with increased slope factors, and delayed the recovery of I A from inactivation, but no significant effects were found on the inactivation of I A. (3) Nano-WC prolonged the evoked action potential duration and lowered the firing rate. These results suggest that 10 -7g/ml nano-WC can decrease the amplitudes of I A and I K currents by reducing the opening number of voltage-gated potassium channels and delaying the recovery of I A from inactivation, which indicate that nano-WC has the potential neurotoxicity.