Fig 1: High voltage-activated potassium channels in MSO neurons. (A) Immunofluorescent staining of Kv3.1b, MAP2 (co-staining left, magnified Kv3.1b image middle) and Kv3.1b blocking peptide (+P, right). Intensity scaling of the gray scaled images is identical, to indicate the effect of the blocking peptide. Line scan intensity profiles are shown as arbitrary units (a.u.) on the right. The line scan was taken from the left image at the position of the gray dotted line. Colors match the color code in the left image. The black line indicates a Gaussian fit on the intensity distributions. Scale bars: left 50 µm, middle 10 µm, right 50 µm. (B) Same as in (A) but for Kv3.2 sub-unit staining. (C) Quantification of the intensity distributions shown in (A,B) and for Kv2.1 and Kv2.2 staining shown in Figure 2. The half width of the Gaussian fit was used to calculate the potassium channel to MAP2 profile for Kv3.1b (n = 7), Kv3.2 (n = 8), Kv2.1 (n = 6), and Kv2.2 (n = 7). Black symbols represent single images, red symbols represent average values. The gray dotted line indicates a distribution profile equivalent to that of MAP2. Larger values indicate a broader, more dendritic distribution profile. (D) Single, digitally extracted MSO neuron stained for Kv3.1b. The position of the line scan is given by the red dotted line. (E) Intensity profile of the line scan shown in (D). Gray area indicates the region of the cell’s nucleus. (F) Normalized intensity distribution of Kv2.1 (n = 13) in single MSO neurons. The edge of the nucleus was defined as zero position. Gray area indicates the region of the soma. Dotted horizontal line indicates the half decay of the normalized intensity. (G) Same as in (F) but for Kv3.1b (n = 6) sub-unit staining. Dotted vertical line indicates the position the intensity reached half of its initial value. (H) Same as in (F) but for Kv3.2 (n = 9) sub-unit staining. Dotted vertical line indicates the position the intensity reached half of its initial value.