Blood pressure (BP) is higher in the activity than in the rest period. This daily BP rhythm has prognostic significance and is mainly attributed to behavioral factors, BP being higher in wakefulness than in sleep. A circadian BP rhythm independent of sleep is debated. Wake-sleep (W-S) episodes occur throughout the 24 hour day in rodents, allowing BP measurements in each W-S state at each time of day. Aim of this study was to investigate whether circadian BP rhythms occur in each W-S state in mice, which are the species of choice for functional genomics. Mice with B6 genetic background (n=26) were implanted with a telemetric BP transducer and electrodes to discriminate W-S states and recorded with 12:12 hours light-dark period. Mean BP values in wakefulness were averaged over 3-hour time bins and analyzed as z-scores. The same procedure was performed in non-rapid eye movement sleep and rapid eye movement (REM) sleep. Analysis of variance evidenced a significant time effect on BP in each W-S state as well as a significant W-S state x time interaction effect. The standard deviation of BP values among time bins was the highest in REM sleep. In an additional group of mice (n=3) recorded for 7 days in constant darkness, Lomb-Scargle periodogram demonstrated significant circadian rhythms of BP in each W-S state in free-running conditions. These findings provide evidence that circadian rhythms of BP occur during each W-S state in mice.
Circadian rhythms of blood pressure occur during each wake-sleep state in mice
SILVANI, ALESSANDRO;BASTIANINI, STEFANO;BERTEOTTI, CHIARA;LO MARTIRE, VIVIANA CARMEN;ZOCCOLI, GIOVANNA
2011
Abstract
Blood pressure (BP) is higher in the activity than in the rest period. This daily BP rhythm has prognostic significance and is mainly attributed to behavioral factors, BP being higher in wakefulness than in sleep. A circadian BP rhythm independent of sleep is debated. Wake-sleep (W-S) episodes occur throughout the 24 hour day in rodents, allowing BP measurements in each W-S state at each time of day. Aim of this study was to investigate whether circadian BP rhythms occur in each W-S state in mice, which are the species of choice for functional genomics. Mice with B6 genetic background (n=26) were implanted with a telemetric BP transducer and electrodes to discriminate W-S states and recorded with 12:12 hours light-dark period. Mean BP values in wakefulness were averaged over 3-hour time bins and analyzed as z-scores. The same procedure was performed in non-rapid eye movement sleep and rapid eye movement (REM) sleep. Analysis of variance evidenced a significant time effect on BP in each W-S state as well as a significant W-S state x time interaction effect. The standard deviation of BP values among time bins was the highest in REM sleep. In an additional group of mice (n=3) recorded for 7 days in constant darkness, Lomb-Scargle periodogram demonstrated significant circadian rhythms of BP in each W-S state in free-running conditions. These findings provide evidence that circadian rhythms of BP occur during each W-S state in mice.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
