Proton-induced Na+ current develops prior to voltage-dependent Na+ and Ca2+ currents in neuronal precursor cells from chick dorsal root ganglion.

Proton-induced Na+ currents (INa(H] were measured in precursor cells from chick dorsal root ganglia with whole-cell patch-clamp recording. Precursor cells were isolated using the method of Rohrer et al. (EMBO. J., 4 (1985) 1709-1714) and fast pH changes were applied with a technique developed by Davies et al. (J. Physiol. (Lond.), 400 (1988) 159-187). Proton-induced transient Na+ currents showing the same properties as in more mature neurons could be elicited already early in differentiation, before high-voltage activated Ca2+ currents and voltage-dependent Na+ currents develop.