Should we get up in the morning? Observations on circadian variations in cardiac events.

Mulcahy, David; Purcell, Henry; Fox, Keith

doi:10.1136/hrt.65.6.299

Cited by 24 publications

(9 citation statements)

References 24 publications

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“…Epidemiological studies have revealed that REM sleep state is an indicator or trigger for the onset of acute cardiovascular accidents such as sudden cardiac death, myocardial infarction, and ischemic stroke (13,17,18). We observed in the present study that there was a large increase and overshoot in RSNA and HR during the transition from REM to NREM/moving states in rats (Fig.…”

Section: Perspectivessupporting

confidence: 65%

Relationship between renal sympathetic nerve activity and arterial pressure during REM sleep in rats

Miki

Kato

Kajii

2003

American Journal of Physiology-Regulatory, Integrative and Comp

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Miki, Kenju, Makiko Kato, and Suzuko Kajii. Relationship between renal sympathetic nerve activity and arterial pressure during REM sleep in rats. Am J Physiol Regul Integr Comp Physiol 284: R467-R473, 2003. First published October 10, 2002 10.1152/ajpregu.00045.2002The relationship between renal sympathetic nerve activity (RSNA) and systemic arterial pressure obtained during rapid eye movement (REM) sleep was compared with that obtained in other sleep and awake states. Electrodes for the measurements of RSNA, electrocardiogram, electromyogram, and electroencephalogram and a catheter for the measurement of systemic arterial pressure were implanted while the animals were under aseptic conditions at least 5 days before the experiment. During the transition from non-REM (NREM) to REM sleep, RSNA and heart rate (HR) decreased immediately by 46 Ϯ 2% (P Ͻ 0.05) and 22 Ϯ 3 beats/min (P Ͻ 0.05), respectively, over 3 s after the onset of REM sleep. Meanwhile, systemic arterial pressure increased gradually after the onset of REM sleep, which was apparently independent of the changes in RSNA. During REM sleep, the relationships between RSNA/HR and systemic arterial pressure were dissociated compared with that obtained during the other behavioral states. These data indicate that the interdependency between systemic arterial pressure and RSNA during REM sleep is likely to be modified compared with other behavioral states.electroencephalogram; heart rate; behavioral states; rapid eye movement RAPID EYE MOVEMENT (REM) sleep results in specific changes in cardiovascular status compared with non-REM (NREM) sleep (22). In humans, systemic arterial pressure initially remains either unchanged or increases during the transition from NREM sleep to REM sleep and thereafter increases further and becomes unstable with a wide range of fluctuation (12,24). Changes in sympathetic nerve activity have been thought to be the main cause for the cardiovascular perturbations occurring during REM sleep (22, 24); however, the functional role of sympathetic nerve activity in regulating systemic arterial pressure during REM sleep remains unclear.Direct measurement of sympathetic nerve activity during REM sleep has been performed in humans and cats, but the findings of the changes in sympathetic nerve activity during REM sleep are not consistent at present. Sympathetic nerve outflow to the muscle vasculature during REM sleep has been measured in humans using microneurography, and it was found to consistently increase during REM sleep (7,19,24). By contrast, Baust et al. (3) using the cat was the first to show a reduction of renal sympathetic nerve activity (RSNA) during REM sleep, which was also reported by Iwamura et al. (8) and Futuro-Neto and Coote (6). The reasons underlying the discrepancy between human and cat observations have not been clarified. Species difference has been pointed out as one possible reason for the difference because systemic arterial pressure decreased consistently in cats (1, 8, 11) while it increased in humans (24). Anoth...

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Section: Perspectivessupporting

confidence: 65%

Relationship between renal sympathetic nerve activity and arterial pressure during REM sleep in rats

Miki

Kato

Kajii

2003

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Whether or not such a time-window contributes to the epidemiological observations that respiratory symptoms, acute mountain sickness, cardiac failures and sudden deaths peak at particular times of the day (Marshall 1977;Muller et al 1985;Richalet et al 1989;Mulcahy et al 1991;Kelmanson 1991;Hayashi et al 1992), is, for the moment, only a matter of speculation. Hopefully, further studies in the mechanisms responsible for the circadian pattern of breathing, while broadening our views on biological functions, will give some physiological insights on the circadian patterns of respiratory diseases.…”

Section: Discussionmentioning

confidence: 93%

Breathing around the clock: an overview of the circadian pattern of respiration

Mortola

2004

European Journal of Applied Physiology

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This article reviews human and animal studies about the circadian patterns of physiological variables involved with the respiratory function. Some measures reflecting the mechanical properties of the lungs, such as functional residual capacity, forced expiratory volumes and airway resistance, change periodically with the time of the day. Also resting pulmonary ventilation (V(E)), tidal volume, and breathing rate follow circadian patterns. In humans, these patterns occur independently of the daily changes in activity, whereas, to some extent, they are linked to changes in the state of arousal. Differently, in some rodents, the circadian oscillations of the breathing pattern occur independently of the daily rhythms of either activity or state of arousal. Recent measurements of the breathing pattern for unlimited periods of time in undisturbed animals have indicated that the circadian changes occur in close temporal phase with those of oxygen consumption, carbon dioxide production, and body temperature. However, none of these variables can fully explain the circadian pattern of breathing, the origin of which remains unclear. Both in humans and in rats the V(E) responses to hypercapnia or hypoxia differ at various times of the day. In rats, the daily differences in V(E) responses are buffered by changes in metabolic rate, such that, unlike humans, the hyperventilation (defined as the increase in ventilation-metabolism ratio) remains constant throughout the 24 h. The presence of a biological clock is a major advantage in the adaptation to the environment, although it forces some variables to deviate periodically from their mean value. In humans, these deviations become apparent in conditions of hypoxia. Hence, a daily time-window exists in which the respiratory system is less capable of responding to challenges, a factor which may contribute to the findings that some cardio-respiratory symptoms and diseases peak at particular times of the day.

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“…Indeed, REM sleep has been implicated in the pathogenesis of cardiac ischemia, myocardial infarction, stroke, and sudden death that occurs in early morning. [7][8][9] Unfortunately, limited information is available as to how changes in sleep states affect integrative regulation of cardiovascular functions.…”

Section: Introductionmentioning

confidence: 99%

Functional Role of Diverse Changes in Sympathetic Nerve Activity in Regulating Arterial Pressure during REM Sleep

Yoshimoto

Yoshida

Miki

2011

Sleep

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1093Sympathetic Nerve Activity and REM Sleep-Yoshimoto et al diac, and splanchnic sympathetic nerve activity were observed, while sympathetic nerve activity to the gastrocnemius muscle increased during an REM-like sleep state induced by physostigmine in the decerebrated cat. Since the study by Futuro-Neto and Coote, to our knowledge, there have been no other reports studying the diverse changes in sympathetic outflow during REM sleep using the same animal. However, sympathetic outflow to different organs has been measured separately during REM sleep. Muscle sympathetic outflow has been consistently found to increase during REM sleep in humans 1,11,12 and rats. 13Renal sympathetic nerve activity (RSNA) has been found to decrease during REM sleep in cats 14,15 and rats. 3 These separate observations in humans and animals suggest that differential changes in sympathetic nerve activity may occur during REM sleep, which is likely to be a key to explain the puzzling responses in cardiovascular functions during REM sleep. However, it is difficult to discuss dynamic interactions between different sympathetic outflows and cardiovascular functions based on separate observations of sympathetic nerve activity in different animals. 16 Thus, to elucidate the neural regulation of cardiovascular function during REM sleep, sympathetic nerve activity must be measured continuously and simultaneously from different organ sites in the same animal during changes in sleep states, but no such attempt has been made so far.This study was designed to investigate whether REM sleep evoked diverse changes in sympathetic outflows and, if so, the functional role of the diverse changes in sympathetic nerve activity in regulating systemic arterial pressure during REM sleep. To this end, RSNA and lumbar sympathetic nerve activity (LSNA), AP and central venous pressure (CVP), HR, electroencephalogram (EEG), and electromyogram (EMG) were measured simultaneously and continuously during the sleepawake cycle in the same rat. INTRODUCTIONCardiovascular functions alter markedly during sleep. During NREM sleep, systemic arterial pressure (AP) is decreased and is stable relative to the active waking states. During REM sleep, in contrast, a puzzling response in cardiovascular function has been consistently observed. In humans, systemic arterial pressure is unstable and increased to levels similar to those during wakefulness, 1 and this was associated with a reduction in cardiac output relative to NREM sleep.2 Consistently in rats AP increased to a level seen during active movement, while heart rate (HR) decreased further compared to NREM sleep. 3,4 Thus, the interdependency between AP and cardiac performance during REM sleep is likely different from the other sleep-awake states.5 Cianci et al. 6 suggested that REM sleep induced loss of integrative control of AP, which may be unfavorable for maintaining and stabilizing organ blood perfusion. Indeed, REM sleep has been implicated in the pathogenesis of cardiac ischemia, myocardial infarction, stroke, and sud...

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Should we get up in the morning? Observations on circadian variations in cardiac events.

Cited by 24 publications

References 24 publications

Relationship between renal sympathetic nerve activity and arterial pressure during REM sleep in rats

Relationship between renal sympathetic nerve activity and arterial pressure during REM sleep in rats

Breathing around the clock: an overview of the circadian pattern of respiration

Functional Role of Diverse Changes in Sympathetic Nerve Activity in Regulating Arterial Pressure during REM Sleep

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