Figure 6. | Optical electrophysiology for probing function and pharmacology of voltage-gated ion channels

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Optical electrophysiology for probing function and pharmacology of voltage-gated ion channels

Figure 6.

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Harvard University, United States; Howard Hughes Medical Institute, Harvard University, United States
Figure 6.
Download figureOpen in new tabFigure 6. Optopatch assay of KV4.3 function.

(A) Voltage clamp recording of KV4.3 current in NaV1.5-KV4.3 Optopatch HEK cells. The bath contained 30 μM TTX to block the NaV1.5 current. Cells were held at −70 mV and then subjected to 1 s steps to −60 mV to +40 mV in 10 mV increments. Peak KV4.3 current densities were 218 pA/pF. (B) NaV1.5-KV4.3-OS HEK cells were probed with simultaneous current clamp and QuasAr2 fluorescence. The cells were stimulated with a pulse of blue light (100 ms, 50 mW/cm2), and QuasAr2 fluorescence was monitored with 640 nm excitation, 400 W/cm2. KV activation led to a narrow action potential width, followed by KV inactivation and a return to steady-state depolarization. (C) Average QuasAr2 fluorescence traces from NaV1.5-KV4.3-OS HEK cells treated with HpTx-2 (n = 3–4 wells for each concentration). (D) Dose-response curve of HpTx-2 on NaV1.5-KV4.3-OS HEK cells. Drug effect was quantified by the fluorescence at the peak repolarization (~40 ms after onset of stimulus) relative to peak fluorescence intensity under 1200 nM HPTX2 treatment.

DOI: http://dx.doi.org/10.7554/eLife.15202.016