Synaptic mechanism of pentylenetetrazole: selectivity for chloride conductance.

In the neurons of Aplysia californica pentylenetetrazole (2 millimolar) greatly reduced chloride-dependent responses to the iontophoresis of putative transmitters. At the same concentration, pentylenetetrazole caused less attenuation of the other iontophoretic responses and had minimal membrane effects. Several convulsants have been observed to have a similar selectivity for the chloride conductance. A common mechanism of convulsant action--reduction of transmitter-induced chloride conductances--is hypothesized.