Transport and localization of the DEG/ENaC ion channel BNaC1 alpha to peripheral mechanosensory terminals of dorsal root ganglia neurons

Mammalian brain sodium channel (BNaC, also known as BNC/ ASlC) proteins for m acid-sensitive and amiloride-blockable sodium channels that are related t o putative mechanosensory channels. Certain BNaC isoforms are expressed exc lusively in dorsal root ganglia (DRG) and have been proposed to form the io n channels mediating tissue acidosis-induced pain. With antibody labeling, we find that the BNaC1 alpha isoform is expressed by most large DRG neurons (low-threshold mechanosensors not involved in acid-induced nociception) an d few small nociceptor neurons (which include high-threshold mechanorecepto rs). BNaC1 alpha is transported from DRG cell bodies to sensory terminals i n the periphery, but not to the spinal cord, and is located specifically at specialized cutaneous mechanosensory terminals, including Meissner, Merkel , penicillate, reticular, lanceolate, and hair follicle palisades as well a s some intraepidermal and free myelinated nerve endings. Accordingly, BNaC1 alpha channels might participate in the transduction of touch and painful mechanical stimuli.