Fig. 8
Stimulatory effects of SAF on the voltage-dependent hysteresis [Hys(V)] behavior of persistent INa [INa(P)] induced by upright isosceles-triangular Vramp. Vramp was supplied for 3.2 s (ramp speed of 0.1 mV/ms; digital-to-analog conversion) to induce Hys(V) behavior in GH3 cells. (A) Current traces during the control period (left) and during the exposure to 10 μM SAF (right). The blue and red traces shown in each panel represent currents induced by the upsloping (ascending) and downsloping (descending) limbs of the upright isosceles-triangular Vramp, respectively. The inset indicates the voltage protocol. The dashed arrows indicate the direction of the current trajectory over time. (B) Summary graphs illustrating the effects of SAF (3 and 10 μM), SAF plus MGB, and SAF plus Ran on the amplitude of Vramp-induced INa(P) measured at −10 mV (ascending limb; left side) and −80 mV (descending limb; right side). Each point represents the mean ± standard error of the mean (n = 7). *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)