Sympathetic Hyperactivity, Sleep Fragmentation, and Wake-Related Blood Pressure Surge During Late-Light Sleep in Spontaneously Hypertensive Rats.
BACKGROUND
Many cardiovascular disease events occur before morning awaking and are more severe in hypertensive patients. Sleep-related cardiovascular regulation has been suggested to play an important role in the pathogenesis. In this study, we explored whether such impairments are exaggerated during late sleep (before the active phase) in spontaneously hypertensive rats (SHRs).


METHODS
Polysomnographic recording was performed through wireless transmission in freely moving SHRs and Wistar-Kyoto rats (WKYs) over 24 hours. The SHRs were injected with saline and an α1-adrenergic antagonist (prazosin: 5 mg/kg) on 2 separate days. Cardiovascular and autonomic functions were assessed by cardiovascular variability and spontaneous baroreflex analysis.


RESULTS
Compared with the early-light period (Zeitgeber time (ZT) 0-6 hours), both the WKYs and SHRs during the late-light period (ZT 6-12 hours) showed sleep fragmentation, sympathovagal imbalance, and baroreflex impairment, which were exaggerated and more advanced in the SHRs. Like the morning blood pressure (BP) surge in humans, we found that there was a wake-related blood pressure surge (WBPS) during the late-light period in both groups of rats. The WBPS was also greater and occurred earlier in the SHRs, and was accompanied by a surge in vascular sympathetic index. Under α1-adrenergic antagonism, the late-light period-related sleep fragmentation and BP surge in the SHRs were partially reversed.


CONCLUSIONS
Our results reveal that sleep-related sympathetic overactivity, baroreflex sensitivity impairment, WBPS, and sleep fragmentation in SHRs deteriorates during the late-light period can be partially alleviated by treatment with an α1-adrenoceptor antagonist.
Sleep Research Center, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan;
Chun-Ting
CT
Lai
Sleep Research Center, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan;
Chun-Yu
CY
Chen
Sleep Research Center, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan; Brain Research Center, National Yang-Ming University, Taipei, Taiwan; Department of Education and Research, Taipei City Hospital, Taipei, Taiwan; Research Center for Adaptive Data Analysis, National Central University, Taoyuan, Taiwan; Chief of Division of Translational Medicine, Stroke & Neurovascular Center, Veterans General Hospital, Taipei, Taiwan.
Terry B J
TB
Kuo
Sleep Research Center, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan; Chief of Division of Translational Medicine, Stroke & Neurovascular Center, Veterans General Hospital, Taipei, Taiwan.
Chang-Ming
CM
Chern
Sleep Research Center, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan; Brain Research Center, National Yang-Ming University, Taipei, Taiwan; Department of Education and Research, Taipei City Hospital, Taipei, Taiwan; cchyang@ym.edu.tw.
Cheryl C H
CC
Yang
D000204:Activity Cycles; D058668:Adrenergic alpha-1 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D017704:Baroreflex; D001794:Blood Pressure / Q000187:drug effects; D002940:Circadian Rhythm; D004195:Disease Models, Animal; D006973:Hypertension / Q000150:complications* / Q000188:drug therapy / Q000503:physiopathology; D008297:Male; D017440:Photoperiod; D017286:Polysomnography / Q000379:methods; D011224:Prazosin / Q000494:pharmacology; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012890:Sleep / Q000187:drug effects; D012892:Sleep Deprivation / Q000188:drug therapy / Q000209:etiology* / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D013686:Telemetry; D013997:Time Factors
D058668:Adrenergic alpha-1 Receptor Antagonists; D000959:Antihypertensive Agents; D011224:Prazosin
blood pressure; hypertension; sleep fragmentation; wake-related blood pressure surge.; α1-adrenergic antagonist