Figure 4.

Characterization of a potassium-current in gm5b, insensitive to TEA and barium (Ba)

(A) IV curve of the muscle fiber at 11°C and 21°C in saline (top), marked with the reversal potential (E_rev, diamond), which is shifted in low K⁺ (0.5K, center) and high K⁺ (2.0K, bottom).

(B) The shift in E_rev follows the Nernst equation, revealing a potassium channel. The horizontal and vertical lines represent the median and standard deviation, respectively (Wilcoxon rank-sum test; 0.5K – 1.0K, p = 0.002; 1.0K - 2.0K, p < 0.0001; 0.5K - 2.0K, p < 0.0001, with p < 0.05/3, where three is the Bonferroni correction).

(C) IV curve at 11°C and 21°C in saline (top) and TEA (10⁻² M, bottom), marked with the reversal potential (E_rev).

(D) The reversal potential is not significantly different in saline and TEA. The horizontal and vertical lines represent the mean and standard deviation, respectively (Paired t test, n = 5, p = 0.8973, p > 0.05).

(E) The difference in current (ΔI) obtained at 21°C and 11°C at −65 mV, compared between saline and TEA, shows no significant difference. The horizontal and vertical lines represent the mean and standard deviation (Paired t test, n = 5, p = 0.9365).

(F) The resting membrane voltage (V_rest) is monitored in gm5b and gm6 at 11°C, 16°C, and 21°C in different solutions: saline (white background), barium 1 mM (Ba, teal), and barium 1 mM with TEA 10-2M (Ba + TEA, lilac). Ba with or without TEA has no effect on the resting membrane voltage (gm5b, n = 3; gm6, n = 4). In each image, each dot represents a single muscle fiber. The dots and the vertical lines represent the median and the SEM.