Document Detail

Intermittent hypoxia increases arterial blood pressure in humans through a Renin-Angiotensin system-dependent mechanism.
MedLine Citation:
PMID:  20625082     Owner:  NLM     Status:  MEDLINE    
Intermittent hypoxia (IH) is believed to contribute to the pathogenesis of hypertension in obstructive sleep apnea through mechanisms that include activation of the renin-angiotensin system. The objective of this study was to assess the role of the type I angiotensin II receptor in mediating an increase in arterial pressure associated with a single 6-hour IH exposure. Using a double-blind, placebo-controlled, randomized, crossover study design, we exposed 9 healthy male subjects to sham IH, IH with placebo medication, and IH with the type I angiotensin II receptor antagonist losartan. We measured blood pressure, cerebral blood flow, and ventilation at baseline and after exposure to 6 hours of IH. An acute isocapnic hypoxia experimental protocol was conducted immediately before and after exposure to IH. IH with placebo increased resting mean arterial pressure by 7.9+/-1.6 mm Hg, but mean arterial pressure did not increase with sham IH (1.9+/-1.5 mm Hg) or with losartan IH (-0.2+/-2.4 mm Hg; P<0.05). Exposure to IH prevented the diurnal decrease in the cerebral blood flow response to hypoxia, independently of the renin-angiotensin system. Finally, in contrast to other models of IH, the acute hypoxic ventilatory response did not change throughout the protocol. IH increases arterial blood pressure through activation of the type I angiotensin II receptor, without a demonstrable impact on the cerebrovascular or ventilatory response to acute hypoxia.
Glen E Foster; Patrick J Hanly; Sofia B Ahmed; Andrew E Beaudin; Vincent Pialoux; Marc J Poulin
Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't     Date:  2010-07-12
Journal Detail:
Title:  Hypertension     Volume:  56     ISSN:  1524-4563     ISO Abbreviation:  Hypertension     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-08-19     Completed Date:  2010-09-13     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7906255     Medline TA:  Hypertension     Country:  United States    
Other Details:
Languages:  eng     Pagination:  369-77     Citation Subset:  IM    
Department of Physiology and Pharmacology and Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
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MeSH Terms
Analysis of Variance
Angiotensin II Type 1 Receptor Blockers / pharmacology
Anoxia / physiopathology*
Blood Pressure / drug effects,  physiology*
Cerebrovascular Circulation / drug effects,  physiology
Cross-Over Studies
Double-Blind Method
Losartan / pharmacology
Receptor, Angiotensin, Type 1 / physiology
Renin-Angiotensin System / drug effects,  physiology*
Grant Support
//Canadian Institutes of Health Research
Reg. No./Substance:
0/Angiotensin II Type 1 Receptor Blockers; 0/Receptor, Angiotensin, Type 1; 114798-26-4/Losartan

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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