Figure 3.

Acute knockdown of Kv4.1 increases spontaneous firing rates in SCN neurons during the day and at night. A, Representative daytime (top) and nighttime (bottom) whole-cell current-clamp recordings obtained from nontargeted shRNA-expressing (left) and Kv4.1-targeted shRNA-expressing (right) SCN neurons are illustrated. B, Mean ± SEM firing frequencies in both nontargeted shRNA-expressing (n = 17–27) and Kv4.1-targeted shRNA-expressing neurons (n = 24–26) are significantly higher during the day than at night. In addition, the mean ± SEM daytime and nighttime firing frequencies in Kv4.1-targeted shRNA-expressing SCN neurons (n = 24–26) are significantly higher than in nontargeted shRNA-expressing (n = 17–27) SCN neurons; p values (one-way ANOVA) are indicated. C, Representative action potential waveforms recorded in nontargeted shRNA-expressing (left) and Kv4.1-targeted shRNA-expressing (right) SCN neurons during the day (top) and at night (bottom) are shown. The records are also illustrated on an expanded time scale in the insets (scale bar, 10 mV and 10 ms). D, The mean ± SEM APD₅₀ values determined in both nontargeted shRNA-expressing (n = 16–26) and Kv4.1-targeted shRNA-expressing neurons (n = 24–26) were not significantly (p > 0.05, one-way ANOVA) different during the day or at night (Table 1).