Figure 4

ROCK inhibitor Y-27632 increases Na_V1.5 activity in SW620 colon cancer cells. (A) Representative whole-cell current recordings obtained from SW620 cells incubated with either vehicle (0.1% DMSO) as a Control (top recordings, blue traces), or 10 µM Y-27632 (bottom, red traces) for 48 h, in response to depolarizing 30-ms pulses from − 95 to + 60 mV in 5-mV steps applied every 2 s from a holding potential of − 100 mV. Dotted lines indicate baseline levels (zero current). (B) Sodium current density–voltage (I_Na-V) relationship for Na_V1.5 channels in SW620 cells in control (0.1% DMSO, n = 23) or 10 µM Y-27632 (n = 33). Peak sodium currents were averaged and plotted as a function of the membrane voltage. (C) Activation- and steady-state inactivation-voltage relationships of Na_V1.5 currents recorded from SW620 cells in absence (control, black-filled circles) and presence (red-filled diamonds) of 10 µM Y-27632. Smooth lines correspond to the Boltzmann’s function fits and the V_1/2 values obtained were the following: V_1/2-activation voltage of − 23.4 ± 0.5 mV and − 26.1 ± 0.4 mV for control and Y-27632, respectively; and V_1/2-inactivation of − 72.2 ± 0.6 mV and − 74.5 ± 0.4 mV for control and Y-27632, respectively. (D, E) Peak- and persistent sodium current densities evoked from a depolarizing step from -100 to − 5 mV in absence (black bars) and presence of 10 µM Y-27632 (red bars) obtained from the same cells than in B. *P < 0.05 and **P < 0.01 (Mann Whitney rank sum test).