Figure 2. Somatic responses in granule cells are unaffected by deletion of K_V10.1.

A–C, electroresponsiveness of cerebellar granule cells of WT and K_V10.1 KO mice. A, representative traces recorded in granule cells from WT (left) and K_V10.1 KO mice (right) in response to injection of square current pulses (bottom). Both genotypes showed inward rectification of the membrane potential during hyperpolarizing pulses and regular spiking after reaching a threshold potential. B, average membrane potential recorded in whole-cell current clamp mode in response to injection of square current pulses (2 s) in the presence of TTX. C, average firing frequency of WT and K_V10.1 KO cells upon injection of 2 s square current pulses ranging between  −35 and +35 pA in 5 pA increments. D–F, AP properties are not altered in K_V10.1 KO mice. D, undershoot amplitudes measured from threshold (a), AP amplitude (b), half-width (c) and 10–90% rise time (d) are compared. Filled bars, WT, n = 11 cells; grey bars, K_V10.1 KO, n = 8 cells. E, representative APs recorded in a WT (left) and K_V10.1 KO (right) granule cell. F, maximum rate of rise of the AP plotted against the maximum rate of fall as determined by analysing the first differential. Filled circles, WT; open circles, K_V10.1 KO. The data points were fitted with straight lines, which were not significantly different between genotypes. The dashed line represents unity.