Figure 3.
Figure 3. Evidence for an intracellular binding site. (A) Perfusion of external 200 µM QX-314 and washout as described in Fig. 2 C shows that QX-314 cannot block expressed NaChBac channels. n = 3. Representative current traces are shown with the zero current lines (dotted lines). Bar, 500 ms. (B) Intracellular injection of QX-314 solution under voltage clamp. Control pulses were performed in Ringer’s solution, depolarizing from −120 to −20 mV at 15-s intervals. Cells were then impaled with the injection electrode while being held at −120 mV. Time between the last pulse of control and after impaling varies from 2 to 3 min. 30 nl of 16.7 mM QX-314 was injected at a holding potential of −120 mV to produce ∼500 µM QX-314 internal concentration. Cells were incubated in Ringer’s solution for 3 min before recording. Injected QX-314 inhibited sodium currents as shown in the current trace (top). n = 6. Error bars represent SEM.

Evidence for an intracellular binding site. (A) Perfusion of external 200 µM QX-314 and washout as described in Fig. 2 C shows that QX-314 cannot block expressed NaChBac channels. n = 3. Representative current traces are shown with the zero current lines (dotted lines). Bar, 500 ms. (B) Intracellular injection of QX-314 solution under voltage clamp. Control pulses were performed in Ringer’s solution, depolarizing from −120 to −20 mV at 15-s intervals. Cells were then impaled with the injection electrode while being held at −120 mV. Time between the last pulse of control and after impaling varies from 2 to 3 min. 30 nl of 16.7 mM QX-314 was injected at a holding potential of −120 mV to produce ∼500 µM QX-314 internal concentration. Cells were incubated in Ringer’s solution for 3 min before recording. Injected QX-314 inhibited sodium currents as shown in the current trace (top). n = 6. Error bars represent SEM.

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