Block of the NMDG⁺ currents by external TEA⁺. Top traces of A and B illustrate the pulse protocols used to induce the currents shown below. The cells were held at −100 mV and depolarized for 12 ms to +40 mV (A) or +20 mV (B) every 2 s. The current recordings were obtained from a cell transiently expressing Kv3.2b channels (A) or a cell stably expressing Kv3.1 channels (B) in the presence of 0 or 10 mM TEA in the external solutions. Extracellular application of 10 mM TEA significantly blocked the inward NMDG⁺ currents both in Kv3.2b and Kv3.1 channels.