Fig. 6
Effect of SAF on INa(T) decay induced by a train of depolarizing pulses in GH3 cells. The train of pulses comprised twenty 40-ms pulses (voltage increased to −10 mV) with 10-ms intervals at −80 mV for a total duration of 1 s. (A) Current traces during the control period (a, blue) and during exposure to 10 μM SAF (b, red). The voltage-clamp protocol used is indicated atop the current traces. In panel A, the third graphs (blue and red) from the top are the expanded forms of the second graphs (brown dashed boxes). (B) The relative amplitude of INa(T) versus pulse train duration in the absence (blue open circles) and presence (red open squares) of 10 μM SAF (mean ± standard error of the mean; n = 7 for each point). The INa(T) amplitudes were normalized by dividing the current amplitudes at the end of each pulse-train stimulation by those obtained at the beginning of the pulse train stimulation. The gray continuous lines on which the data points are overlaid are reliably fitted with a single exponential. (C) Summary graph depicting the effects of SAF (3 and 10 μM), SAF plus ranolazine (Ran), and SAF plus MGB on the decaying time constant of the current induced by a train of depolarizing command voltages ranging from –80 to –10 mV (mean ± standard error of the mean; n = 7 for each point). *Significantly different from the control (P < 0.05), **significantly different from the SAF (3 μM) alone group (P < 0.05), and +significantly different from the SAF (10 μM) alone group (P < 0.05)