Age-related changes in control of blood pressure and heart rate during sleep in the rat.
OBJECTIVE
The aim of this study was to determine age-related changes in the control of mean arterial pressure (MAP) and heart rate (HR) during sleep, and its relationship to the baroreflex in aging.


METHODS
MAP, HR, body temperature (TP), spontaneous activity (ACT), and sleeping/waking duration were monitored for 24 hours in groups of young (10-12 wk old) and old (23-24 mo old) rats.


METHODS
The sleep laboratory at the University of Tokushima.


METHODS
Subjects were 8 young (10-12 wk old) and 7 old (23-24 mo old) Wistar rats.


METHODS
Reflex control of HR was evaluated by examining various pressure responses to an intravenous bolus injection of phenylephrine and sodium nitroprusside.


RESULTS
MAP and TP were recorded by a radiotelemetry system. HR was detected from the AP signal. ACT was counted by a photo-sensor system. In the case of old rats, the sensitivity of baroreflex control of HR was significantly depressed, and the spontaneous increase of MAP and HR during REM sleep and the MAP drop at the end of REM sleep were significantly enhanced. The old rats showed no large deterioration of the circadian profiles of MAP, HR, TP, and the amount of sleep.


CONCLUSIONS
The baroreflex dysfunction is considered to appear in an early stage of the aging process, and to affect the control of MAP and HR during sleep.
Sei
Hiroyoshi
H
Department of Physiology, School of Medicine, The University of Tokushima, Japan. sei@basic.med.tokushima-u.ac.jp
Sano
Atsuko
A
Ohno
Hiromi
H
Yamabe
Kazue
K
Nishioka
Yasuhiko
Y
Sone
Saburo
S
Morita
Yusuke
Y
D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000818:Animals; D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001831:Body Temperature / Q000502:physiology; D004567:Electrodes, Implanted; D004569:Electroencephalography; D006339:Heart Rate / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012890:Sleep / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology