Fig. 8.

TTX-sensitive and TTX-resistant Na⁺ currents do not contribute to neuronal excitability in the caps⁻lpH⁺ neurons. a Steady-state activation of TTX-sensitive, TTX-S, component of Na⁺ current. Insert: representative traces of TTX-S Na⁺ current b A part of a low voltage region from A is presented in a larger scale demonstrating negligible values of TTX-S current at depolarization steps in a range of −70 - -50 mV (n = 9 from three rats). c Steady-state activation curve of TTX-resistant, TTX-R, component of Na⁺ current demonstrating its activation threshold at −35 mV (n = 9 from three rats). Insert: representative traces of TTX-R Na⁺ current. Altogether these results demonstrate a lack of low-threshold TTX-R current and substantially lower density of TTX-S current compared to T-type current [39] at depolarization steps up to -40 mV