Activation gating in HCN2 channels
Fig 1
Multiple time courses of Po covering a wide voltage range for HCN2 channel gating.
Currents were activated by hyperpolarizing pulses to the voltage Va with the duration ta followed by depolarizing pulses to the voltage Vd to generate deactivation. (a) Representative current trace. Va = - 140 mV, ta = 4 s, Vd = -40 mV. (b) Steady-state activation in the absence of cAMP and in the presence of 10 μM cAMP. The Boltzmann curves, obtained with pulses of 4 s duration, were computed according to a previous report by equation S1 [47]. The values were: no cAMP: z = 5.15, Vh = -118.4 mV; 10 μM cAMP: z = 4.88, Vh = -97.1 mV. The blue and red arrows indicate the used values of Va and Vd, respectively. (c) Set of Po traces following 27 different double pulse protocols in the absence of cAMP. Va = -140 mV: ta = 0.3 s, 1 s, 4 s; Va = -125 mV: ta = 0.5 s, 2 s, 11 s; Va = -110 mV: ta = 1.5 s, 5 s, 15 s (n = 5–18). (d) As c but in the presence of cAMP. Va = -130 mV: ta = 0.15 s, 0.3 s, 3 s; Va = -100 mV: ta = 0.5 s, 2 s, 11 s; Va = -90 mV: ta = 1.5 s, 5 s, 15 s. In c and d Vd was -40 mV, 20 mV, 80 mV (n = 7–10).