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Figure 5. Effect of DHA on the early activation steps versus the opening step. (A) A simple scheme for the ion channel kinetics. C0 to C4 denote closed states with 0–4 activated voltage sensors where the voltage sensors move independently of each other. O is the open state. (B) Theoretical G-V curves and Q-V curves for WT-IR and the ILT channel generated from the model in A. For calculations, see Eqs. 4–7 in Materials and methods. (C) 70 µM DHA at pH 9.0 increases the ion current at +60 mV in the ILT channel. Holding voltage is −80 mV. (D) The G-V curve is shifted −30 mV for the ILT channel. Eq. 2 is fitted to the experimental data as explained in Materials and methods. V1/2 = 118 mV for control and 88 mV for DHA. s = 22.6 mV and A = 0.271 mS in both curves. (E) Integrated OFF gating currents from the ILT/W434F mutation (n = 3). 70 µM DHA at pH 9.0 shifts the control curve −5 mV. (F and G) Calculated effects of DHA on open probability (F; G-V) and gating charge movement (G; Q-V) using Eqs. 4–7. Continuous lines are control curves. Dashed curves are DHA-affected curves. DHA was set to shift Vαβ with −5 mV and Vγδ with −30 mV for both channels. (H) Summary of DHA-induced shifts from both experiments and models. Data are expressed as mean ± SEM (n = 3–9). Image published in: Börjesson SI and Elinder F (2011) © 2011 Börjesson and Elinder. Creative Commons Attribution-NonCommercial-ShareAlike license Larger Image Printer Friendly View

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