[30] Pore-blocking toxins as probes of voltage-dependent channels

This chapter discusses some areas in which understanding of voltage-dependent Na+ channels has been, and may further be, illuminated by judicious experiments with pore-blocking toxins. The chapter describes briefly both experimental methods and analytical approaches that are providing new glimpses of the molecular basis of Na+ channel function. These studies have the potential to yield new details about the molecular geometry of the ion-conducting pore and provide clues about the packing of channel domains, the interactions between charged ligands and the pore, interactions between pairs of blocking ions within the pore, and the proximity and interactions of the voltage-sensitive gating machinery with the charged entities within the pore.