Document Detail


Effect of repetitive hypoxic apnoeas on baroreflex function in humans.
MedLine Citation:
PMID:  16709638     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Baroreflex function is impaired in patients with obstructive sleep apnoea. We tested the hypothesis that short-term exposure to repetitive hypoxic apnoeas (RHA) produces prolonged impairment in baroreflex function. Baroreflex function was determined using the modified Oxford technique in 14 subjects (26 +/- 1 years). Baroreflex sensitivity (BRS) was quantified from the R-R interval-systolic blood pressure (BP; cardiovagal BRS), heart rate-systolic BP (HR BRS) and muscle sympathetic nerve activity (MSNA)-diastolic BP (sympathetic BRS) relations. RHA involved subjects performing repetitive end-expiratory apnoeas (20 s) every minute for 30 min during intermittent hypoxia to accentuate oxygen desaturation. After RHA, BP and MSNA at rest were elevated. BRS was measured approximately 7 (Post 1), approximately 30 (Post 2) and approximately 50 min (Post 3) after RHA to provide insight into the temporal pattern of responses. Cardiovagal BRS (16.8 +/- 1.3, 16.5 +/- 1.6, 17.6 +/- 2.0 and 17.4 +/- 1.5 ms mmHg(-1) for Pre, Post 1, Post 2 and Post 3, respectively), HR BRS (-1.1 +/- 0.1, -1.1 +/- 0.1, -1.3 +/- 0.1 and -1.4 +/- 0.1 beats min(-1) mmHg(-1)) and sympathetic BRS (-4.5 +/- 0.6, -4.4 +/- 0.7, -3.7 +/- 0.5 and -4.7 +/- 1.0 arbitrary units (au) beat(-1) mmHg(-1)) were unchanged by RHA. In contrast, the operating points of the baroreflexes were shifted rightward (to higher levels of BP) and upward (to higher levels of heart rate and MSNA) after RHA (P < 0.05). Time control studies performed in five additional subjects showed no change in any of the measured variables over time. Collectively, these data indicate that short-term exposure to RHA shifts ('resets') the baroreflex stimulus-response curve to higher levels of BP without influencing BRS for extended periods of time.
Authors:
Kevin D Monahan; Urs A Leuenberger; Chester A Ray
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2006-05-18
Journal Detail:
Title:  The Journal of physiology     Volume:  574     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2006 Jul 
Date Detail:
Created Date:  2006-07-17     Completed Date:  2006-09-18     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  605-13     Citation Subset:  IM    
Affiliation:
Penn State Heart and Vascular Institute, General Clinical Research Center, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA. kmonahan@psu.edu
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Adult
Anoxia / etiology*,  physiopathology*
Baroreflex / physiology*
Blood Pressure / physiology
Carbon Dioxide / metabolism
Female
Heart Rate / physiology
Humans
Male
Oxygen / metabolism
Sleep Apnea, Obstructive / complications*,  physiopathology*
Sympathetic Nervous System / physiology
Time Factors
Grant Support
ID/Acronym/Agency:
C06 RR016499/RR/NCRR NIH HHS; CA00404/CA/NCI NIH HHS; DC006459/DC/NIDCD NIH HHS; HL68699/HL/NHLBI NIH HHS; HL77670/HL/NHLBI NIH HHS; M01 RR10732/RR/NCRR NIH HHS
Chemical
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen
Comments/Corrections

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