Figure 6. Sympathovagal imbalance and arrhythmias in HD during rest period.

(A) Representative ECG trace in freely moving conscious animals allowing HR (bpm) measurement in WT and Q175 mice treated or not with S107 or ARM036 during light (rest period) and dark (awake period) cycles. (B) HR (bpm) average during awake and rest periods in WT (n = 5), Q175 (n = 8), and Q175 mice treated or not with S107 (n = 6) or ARM036 (n = 6). (C) HR average record. Hexamethonium injection (20 mg/kg) had moderate effects on HR related to suppression of cardiac autonomic control of HR, that is, lowering HR during the daylight period in Q175 (n = 6) and Q175 mice treated or not with S107 (n = 6) or ARM036 (n = 6). Data (mean ± SD) analysis was performed by 1-way ANOVA. Bonferroni’s posttest revealed *P < 0.05 vs. WT, ^#P < 0.05 vs. Q175 at rest period. Student’s t test, ^$P < 0.05 rest vs. awake period and baseline vs. hexamethonium. (D and E) Low-frequency (LFr) spectral power density measured by HRV analysis using fast Fourier transformation (LFr: 0.15–1.5 Hz) in WT, Q175, Q175+ARM036, and Q175+S107 during rest and awake periods (n = 5–8 mouse/group). (F and G) High-frequency (HFr) spectral power measured by HRV analysis using fast Fourier transformation (HFr: 1.5–5 Hz) during rest and awake periods in WT, Q175, Q175+ARM036, and Q175+S107 (n = 5–8 mouse/group). (H and I) LFr/HFr ratio (n = 5–8 mouse/group). (J and K) Number of isolated and triplet (3 consecutive) ventricular extrasystoles (VESs) during 10 hours in WT, Q175, Q175+ARM036, and Q175+S107 during rest and awake periods (n = 5–8 mouse/group). Comparison of HRV (standard deviation of NN intervals) and VESs at rest versus awake is shown in Supplemental Figure 5, D–F. Representative example of VESs in Q175 mice is shown in Supplemental Figure 5G. Data (mean ± SD) analysis was performed by 1-way ANOVA. Bonferroni’s posttest revealed *P < 0.05 vs. WT, ^#P < 0.05 vs. Q175. Scale bar: 110 ms.