Table 2.

Expression in tissues and TTX sensitivity of Na_V channel subtypes.

NaV subtype	Gene	Expression in tissues	TTX sensitivity
NaV1.1	SCN1A	simple − PNS (DRG) simple − CNS (hippocampus, neocortex, cerebellum, retinal ganglion, microglia) simple − Keratinocytes	Yes
NaV1.2	SCN2A	simple − PNS (DRG; unmyelinated or pre-myelinated axons and dendrites) simple − CNS (hippocampus, neocortex; cerebellum, astrocytes) simple − Fibroblast, islet β-cells, odontoblasts, osteoblasts	Yes
NaV1.3 (fetal)	SCN3A	simple − PNS (early postnatal periods, adult DRG when nerve injury or inflammation, Schwann cells) simple − CNS (hippocampus, neocortex) simple − Fibroblasts, islet β-cells	Yes
NaV1.4	SCN4A	simple − Skeletal muscle	Yes
NaV1.5	SCN5A	simple − Heart simple − Skeletal muscle (denervated or fetal)	No
NaV1.6	SCN8A	simple − PNS (DRG, nodes of Ranvier of motoneurons, Schwann cells) simple − CNS (Purkinje, pyramidal and granule neurons, nodes of Ranvier and axon initial segment of axons, astrocytes, microglia) simple − Cancer cells, endothelial cells, fibroblasts, keratinocytes, macrophages	Yes
NaV1.7	SCN9A	simple − PNS (DRG and sympathetic ganglion neurons, neuroendocrine cells) simple − CNS (olfactory sensory neurons) simple − Smooth myocytes simple − Prostate and breast tumor cells, human erythroid progenitor cells, fibroblasts, immune cells	Yes
NaV1.8	SCN10A	simple − PNS (DRG) simple − CNS (Purkinje neurons, astrocytes, Müller glia) simple − Endothelial cells, fibroblasts, keratinocytes, T lymphocytes	No
NaV1.9	SCN11A	simple − PNS (DRG) simple − CNS (hypothalamus, astrocytes, Müller glia) simple − Cancer cells, endothelial cells, fibroblasts, T lymphocytes	No
NaV1.10 (NaV1.x, NaV2.1-2.3)	SCN7A	simple − Lung, uterus, heart simple − PNS (DRG, Schwann cells) simple − CNS (thalamus, hippocampus, cerebellum, median preoptic nucleus)	No

The table illustrates the expression in tissues and sensitivity to TTX of Na_V channel α-subunits (adapted from Goldin, 2001; Trimmer and Rhodes, 2004; Black and Waxman, 2013). TTX, tetrodotoxin; PNS, peripheral nervous system; DRG, dorsal root ganglia; CNS, central nervous system.