Figure 3.
The kinetics of recovery from steady-state inactivation suggests that IKA in both wild-type and fmr1-/y neurons is mediated by KV4-containing channels. A, Representative traces showing the slower inactivation of IKA at 50 mV (thick trace) compared with 0 mV (thin trace) in a dendritic patch from a wild-type neuron (A1) and an fmr1-/y neuron (A2). The traces are scaled to peak an on an expanded time scale below. B, τinact of IKA is less voltage dependent in fmr1-/y dendrites compared with wild-type dendrites. C, The slope of the fit to the voltage dependence of τinact for fmr1-/y patches is significantly smaller than wild-type patches. D, The mean τinact for the maximum IKA is significantly faster in fmr1-/y patches (wild-type: n = 8 patches, 8 mice; fmr1-/y: n = 6 patches, 5 mice; *p < 0.05 vs wild-type). E, Steady-state inactivation of dendritic A-type K+ channels is not significantly different between wild-type and fmr1-/y neurons. Inset, Representative traces and voltage protocol used to measure steady-state inactivation (wild-type: n = 4 patches, 3 mice; fmr1-/y: n = 4patches, 4 mice). F, Recovery from steady-state inactivation for dendritic A-type K+ channels from wild-type and fmr1-/y neurons. G, Group data showing the time constant of recovery from steady-state inactivation of dendritic A-type K+ channels for wild-type and fmr1-/y neurons is not significantly different. Note the τrecovery for both wild-type and fmr1-/y neurons is consistent with KV4 containing A-type K+ channels. For wild-type: n = 5 from 5 mice; fmr1-/y: n = 4 from 4 mice.