Fig. 5: Characterization of IKCa-channel activity in undifferentiated amniotic fluid-derived stem cells (AFSCs).
a Original IKCa-channel currents were obtained at 0 mV relative to the bath. The downward deflection indicates the opening event of the undifferentiated AFSC IKCa channel. b A single IKCa-channel amplitude (n = 9 for each point) was plotted as a function of potential (i.e., Δvoltage). Notably, as the patch potential is the sum of the resting potential and the pipette potential, these inward currents reverse at approximately +65 mV. As different levels of membrane potential were applied to the undifferentiated AFSCs, the I–V relationship for IKCa channels (i.e., single-channel amplitude versus Δvoltage) was established. The single-channel conductance was 28.1 ± 1.1 pS (n = 9). Moreover, the dashed line indicates the reversal of potential (i.e., + 65 mV). c The effects of TRAM-34 (1 μM), TRAM-39 (1 μM), or verruculogen (Verr, 1 μM) on the probability of IKCa-channel openings were investigated (n = 9 for each bar). The opening events of IKCa channels were measured at 0 mV relative to the bath solution. The addition of either TRAM-34 (1 μM) or TRAM-39 (1 μM) significantly decreased the probability of IKCa-channel openings (control vs. TRAM-39: 0.011 ± 0.001 vs. 0.0015 ± 0.0005, p = 0.001), while verruculogen (1 μM) did not have any effect (control vs. verruculogen: 0.011 ± 0.001 vs. 0.0011 ± 0.0014, p = 0.06) *Significantly different from the control (p < 0.05). 1-[(2-Chlorophenyl)diphenylmethyl]-1H-pyrazole indicates TRAM-34; 2-chloro-α,α-diphenyl benzeneacetonitrile, TRAM-39
