TY - JOUR T1 - Differential properties of tetrodotoxin-sensitive and tetrodotoxin- resistant sodium channels in rat dorsal root ganglion neurons JF - The Journal of Neuroscience JO - J. Neurosci. SP - 2104 LP - 2111 DO - 10.1523/JNEUROSCI.12-06-02104.1992 VL - 12 IS - 6 AU - ML Roy AU - T Narahashi Y1 - 1992/06/01 UR - http://www.jneurosci.org/content/12/6/2104.abstract N2 - TTX-sensitive (TTX-S) and TTX-resistant (TTX-R) sodium channel currents were analyzed in acutely dissociated dorsal root ganglion (DRG) neurons isolated from 3–12-d-old and adult rats. Currents were recorded using the whole-cell patch-clamp technique. TTX-R current was more likely to be present in younger animals (3–7 d), whereas TTX-S current was more common in older animals (7–10 d), although TTX-R current was recorded from adult rat DRG neurons. The TTX-R and TTX-S currents differed in their steady-state inactivation, with 50% inactivation voltage at -40 +/- 5 mV (n = 10) for TTX-R currents and -70 +/- 4 mV (n = 10) for TTX- S currents. These current types also differed in their activation kinetics, with 50% activation values of -15 +/- 5 mV (n = 5) for TTX-R currents and -26 +/- 6 mV (n = 5) for TTX-S currents. The interactions of TTX-R and TTX-S channels with various pharmacological agents and divalent cations were studied. The Kd values for TTX-S and TTX-R currents were estimated to be 0.3 nM and 100 microM for TTX, 0.5 nM and 10 microM for saxitoxin, and 50 microM and 200 microM for lidocaine, respectively. TTX-S channels did not exhibit a marked use-dependent block by lidocaine, whereas lidocaine significantly decreased TTX-R current in a use-dependent manner at frequencies ranging from 1 to 33.3 Hz. Several external divalent cations exerted different effects on these current types.(ABSTRACT TRUNCATED AT 250 WORDS) ER -