Figure 1.
Mean activity, blood pressure and heart rate in WT and Vipr2−/− mice in a light-dark cycle.
Activity (a, d), mean arterial pressure (MAP: b, e) and heart rate (c, f) were measured over 60 h. Values plotted are hourly means (± SEM, n = 5) for groups of WT (a–c) and Vipr2−/− (d–f) mice. Solid lines represent data smoothing using the weighted average of the 9 nearest points [26]. The bars at the top of each panel indicate the dark period in black and the light period in white.
Figure 2.
Activity, blood pressure and heart rate in individual WT and Vipr2−/− mice in a light-dark cycle.
Activity (a, d), mean arterial pressure (MAP: b, e) and heart rate (c, f) were measured over 60 h in representative individual WT (a–c) and Vipr2−/− (d–f) mice. The bars at the top of each panel indicate the dark period in black and the light period in white.
Figure 3.
K-means clustering of the durations of periods of activity in WT mice in a LD cycle showing a bimodal distribution.
Table 1.
Time spent in short “ultradian” and long periods of rest and sleep.
Figure 4.
Rhythms of resting blood pressure and heart rate.
Panels a – d show mean (± S.E.M., n = 5) heart rate (a, c) and MAP (b, d) during periods of inactivity, averaged over 2 h time periods across 24 h, extracted from 10 day recordings from WT (-•-) and Vipr2−/− (-□-) mice in a light-dark cycle (LD: a, b) and in constant conditions (DD: c, d). The bars at the top indicate the dark period in black and the light period in white (a, b) or subjective night in black and subjective day in gray (c, d). In (e–l), average Chi-square periodograms were constructed (using a formula appropriate for records containing gaps) from “binned” heart rate (e, g, i, k) and MAP (f, h, j, l) records (4 min bins) from WT (e–h) and Vipr2−/− (i–l) mice (n = 5 of each genotype) over 10 day periods in a light-dark cycle (LD: e, f, i, j) and in constant conditions (DD: g, h, k, l). The Qp statistic was calculated for periods between 5 and 28 h. The Qp statistic represents the degree to which each period is present in the data, after accounting for differences due to chance. Dashed lines indicate the value of Qp required to achieve statistical significance (P<0.01). Where significant rhythmicity was found, the estimate of τ, the circadian period, is shown.
Figure 5.
Sleep patterns of individual Vipr2−/− and wild-type mice under entrained (LD) and constant (DD) conditions.
Representative records of wake/sleep patterns from individual WT (a, c) and Vipr2−/− (b, d) mice in LD (a, b) and DD (c, d) conditions. Values plotted are the percentage of each 5 min interval during which animals were awake; the bars at the top indicate the dark period in black and the light period in white (a, b) or subjective night in black and subjective day in gray (c, d).
Figure 6.
Sleep patterns of Vipr2−/− and wild-type mice under entrained (LD) conditions.
Baseline sleep patterns for six wild-type control mice (black symbols) and seven Vipr2−/− (white symbols) under entrained (LD 12∶12) conditions are shown. In a, c and e, the time in each sleep stage is shown as a percentage of the recording time in 2 h intervals (mean ± SEM). The bars at the top indicate the dark period in black and the light period in white. * indicates significant differences (P<0.05) between mouse genotypes at that time point (RM-ANOVA df = 1,11; Fisher's post-hoc). b, d and f show sleep times averaged over the entire 24 h recording period as well as during both the 12 h light and 12 h dark phase (mean ± SEM). Significant differences between genotypes are shown: * = P<0.05, ** = P<0.005, *** = P<0.0005; t test for independent samples. NREM = non-rapid eye movement; REM = rapid eye movement.