STRUCTURE AND FUNCTION OF A NOVEL VOLTAGE-GATED, TETRODOTOXIN-RESISTANT SODIUM-CHANNEL SPECIFIC TO SENSORY NEURONS

Small neurons of the dorsal root ganglia (DRG) are known to play an im portant role in nociceptive mechanisms. These neurons express two type s of sodium current, which differ in their inactivation kinetics and s ensitivity to tetrodotoxin. Here, we report the cloning of the alpha-s ubunit of a novel, voltage-gated sodium channel (PN3) from rat DRG. Fu nctional expression in Xenopus oocytes showed that PN3 is a voltage-ga ted sodium channel with a depolarized activation potential, slow inact ivation kinetics, and resistance to high concentrations of tetrodotoxi n. In situ hybridization to rat DRG indicated that PN3 is expressed pr imarily in small sensory neurons of the peripheral nervous system.