Efferent-mediated slow excitation requires KCNQ channels. A, B, Excitatory responses of CD afferent to short efferent shock trains (20 shocks at 200/s; black bars, n = 20) are shown as continuous rate histograms before (A) and after (B) 10 μm XE991. C, Corresponding average response histograms for efferent-mediated fast excitation during control and XE991 were constructed from data in A and B, respectively. D, Peak efferent-mediated fast excitation (left, n = 8) and peak slow excitation (right, n = 6) in CD afferents are plotted before (Cntl; open symbols) and after (filled symbols) the administration of XE991. Triangles and dashed lines represent units shown in A and B.