Brain-derived neurotrophic factor (BDNF)-induced activation of TrkB causes current suppression of Kv1.3 current that is blocked by adaptor proteins nShc or Grb10. (A-D) Human embryonic kidney 293 (HEK293) cells were transiently transfected with cDNA encoding Kv1.3 channel plus TrkB kinase with modified conditions as noted. Macroscopic currents were recorded in the cell-attached configuration by holding patches at (Vh) = -90 mV and stepping to a single depolarizing potential of +40 mV (Vc) for 1000 ms at an interpulse frequency of 45 s. Recording pipettes were back-filled with 1 ng/μl BDNF (BDNF) or control solution (vehicle) and tip-filled with control patch solution to monitor change in kinase activation over time. Time 0 = represents current evoked upon stable seal formation, Time 20 = post-neurotrophin treated patch 20 minutes later. (E) Histogram plot of the peak current amplitude for various transfection conditions and recordings as in (A-D). Data are normalized as a ratio of final current over initial current (I20/I0) and are expressed as mean ± standard error of the mean (S.E.M.); sample size as indicated. * = statistically significant by paired t-test at α ≤ 0.05. Dashed line = ratio of 1.0 or no change post-neurotrophin stimulation.