Figure 6

Chronic activity blockade or prolonged NMDAR inhibition reduces protein and current expression of K ⁺ channels. (A) Immunoblot analyses confirming activity-dependent modulation of the principle and auxiliary subunits of K_v1 channels (K_v1.1, K_v1.4, Lgi1) and K_v7/KCNQ channels (K_v7.3) following 48 h application of TTX or BC (n = 6–12 per treatment). The level of each protein was normalized to GAPDH, followed by normalization to CTL-H₂O. (B-E) Voltage clamp recordings of K⁺ currents evoked by depolarizing voltage step to +40 mV in cultured hippocampal neurons (DIV 12–14) following 48 h treatment with CTL, TTX or APV. After recording total K⁺ currents under vehicle control (0.1% H₂O), dendrotoxin-K (DTX-K, 100 nM) or XE991 (10 μM) were applied and recordings of K⁺ currents from the same neurons were repeated. (B,C) Representative traces of K⁺ currents before (top, black) and after (middle, gray) application with K_v1 channel specific antagonist, DTX-K (B) or K_v7/KCNQ channel specific antagonist, XE991 (C). The DTX-K- and XE991-sensitive currents were isolated by subtraction (bottom, red). (D) Enlargement of the traces from DTX-K-and XE991-sensitive K⁺ currents in neurons treated for 48 h with CTL (black), TTX (orange), or APV (blue). (E) Summary plots illustrating the effect of 48 h treatment with CTL (n = 21), TTX (n = 22), or APV (n = 22) on total K⁺ currents and DTX-K-and XE991-sensitive K⁺ currents at +40 mV. (A,E) Mean ± SEM (*p < 0.05, **p < 0.01).