Figure 1.

Quaternary ammonium (QA) ions are high-affinity inhibitors of K2P channels. (A) TRESK channel currents expressed in Xenopus oocytes measured at –80 mV in inside-out patches exposed to 5 μM of the indicated QA ions. (B) Application of 100 μM of TEA and TButA and 10 μM TPenA and THexA on TREK-1. (C) Representative current trace for determining the high-affinity block by TPenA in TREK-1. (D–F) Summary of IC₅₀ values for current inhibition measured for TRESK (n⩾5 experiments for each blocker), TREK-1 (n⩾4 experiments for each blocker) and TASK-3 (n⩾3 experiments for each blocker) channels determined for different chain length QA ions (note that for TREK-1, the IC₅₀ for TEA was estimated due to insufficient block at very high concentrations).