Tetrodotoxin-sensitive sodium channels in normal human fibroblasts and normal human glia-like cells.

Tetrodotoxin-sensitive sodium channels are detectable in normal human fibroblasts and in "glia-like" cells at appreciable levels when compared to what is observed in established neuronal cell lines in culture. Two- to 3-fold stimulations of sodium influx are observed in the presence of 0.2 mM veratridine and scorpion venom at 0.1 mg/ml. Tetrodotoxin (2 microM) inhibits the observed stimulation of sodium influx. Previous work has indicated that these neurotoxins act on the voltage-sensitive sodium ionophore of excitable cells, and the presence of such channels in cells generally considered nonexcitable raises questions regarding both the uniqueness of this ionophore as a property of excitable cells and the origin of the cells generally described as fibroblasts.