Fig. 3

Effect of TCE on the use-dependent inactivation of TTX-R Na⁺ channels. (A) A schematic illustration of voltage step pulses to examine the use-dependent inhibition of TTX-R Na⁺ channels. The TTX-R I_Na was induced by 40, 100, and 200 successive voltage step pulses (− 80 mV to − 10 mV, 10 ms duration, 2 Hz, 5 Hz, and 10 Hz, respectively). (B) Typical traces of TTX-R I_Na elicited by 200 successive voltage step pulses (10 Hz) in the absence (left) and presence (right) of 3 mM TCE. (C) Time courses of the amplitude of TTX-R I_Na during trains of 40 (2 Hz, a), 100 (5 Hz, b), and 200 pulses (10 Hz, c) in the absence (black circles) and presence (red circles) of 3 mM TCE. Each point represents the mean and SEM from eight experiments. (D) TCE-induced changes in the P₄₀/P₁ (2 Hz, a), P₁₀₀/P₁ (5 Hz, b), and P₂₀₀/P₁ (10 Hz, c) ratios of TTX-R I_Na. The ratios were normalized to the respective control (dotted lines). Each column represents the mean and SEM from eight experiments for 1, 3, and 10 mM TCE. *; p < 0.05, **; p < 0.01, n.s; not significant