XB-IMG-123451
Xenbase Image ID: 123451
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Figure 2. Voltage dependence of Shaker IR channel availability in the presence of external TEA. (A) Ionic currents in the absence of TEA elicited after the protocol schematized at the top of the figure. This protocol consisted of a 60-s prepulse to voltages usually ranging from â70 to â15 mV with 5-mV steps. At the end of this period, channel availability was tested with a pulse to +50 mV. (B) Similar traces in the presence of 40 mM TEACl replacing an equivalent concentration of NaCl. (C) Comparison of the peak current amplitude at the test voltage pulse for the control traces shown in A (open circles) and the 40-mM external TEA traces in B (filled circles). The continuous lines are fits to a Boltzman distribution function with the half inactivation voltages depicted in the figure and an effective valence of z = â6.34 eo for the control traces and z = â6.63 eo for the TEA traces. HP, the holding voltage was â90 mV. Discontinuous lines in A and B indicate zero current level. (Inset) Activation relationship measured at the end of a 50-ms pulse taken before (open circles) and after (filled circles) the inactivation protocols for the experiments shown. Conductances were calculated assuming a reversal potential of â100 mV. Continuous lines are a Boltzman distribution equation with V0.5 = â20.0 and â21.7 mV for the before and after data, respectively, with effective valences of 3.2 and 3.3, respectively. Image published in: González-Pérez V et al. (2008) © 2008 González-Pérez et al. Creative Commons Attribution-NonCommercial-ShareAlike license Larger Image Printer Friendly View |