Selective blockade of P-type calcium channels by lead in cultured hippocampal neurons.

The effects of lead ions (Pb2+) on neuronal calcium channels were examined in cultured hippocampal neurons. Pb2+ blocked calcium channels in a concentration-dependent manner. The current-voltage relationship of the inhibition suggested a selective blockade of high-threshold calcium channels by Pb2+ up to a concentration of 3 microM. Pb2+ (3 microM) preferentially suppressed the omega-agatoxin IVA-sensitive components of the calcium channels. These findings suggest that Pb2+ mainly affects the P-type calcium channels at low concentrations.