High titer antibody to mammalian neuronal sodium channels produces sustained channel block

Antibodies specific for neuronal sodium channels recognized the alpha and beta subunits of the voltage-gated sodium channel on immunoblots of crude rat and cat brain membranes and purified rat brain sodium channels. These antibodies did not recognize channels from rat cardiac or rabbit skeletal muscle. Antibody binding to blots of crude rat brain membranes was blocked by preabsorption of the antibody with purified rat brain sodium channels. Staining of the sodium channel alpha subunit on immunoblots of crude rat brain membranes was easily visualized at antibody dilutions of up to 1:150,000, which is at least 15-fold higher than that reported in previous studies. Addition of antibody produced in one chicken to the extracellular face of batrachotoxin-activated rat brain sodium channels in planar lipid bilayers produced a sustained block of the channel at either hyperpolarized (-65 to -45 mV) or depolarized potentials (+45 to +75 mV). This block was not produced when the antibody was added to the cytoplasmic face of the channel, or if preimmune antibody was added to the extracellular face of rat brain sodium channels.