Document Detail


Ventilatory, hemodynamic, sympathetic nervous system, and vascular reactivity changes after recurrent nocturnal sustained hypoxia in humans.
MedLine Citation:
PMID:  18539753     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Recurrent and intermittent nocturnal hypoxia is characteristic of several diseases including chronic obstructive pulmonary disease, congestive heart failure, obesity-hypoventilation syndrome, and obstructive sleep apnea. The contribution of hypoxia to cardiovascular morbidity and mortality in these disease states is unclear, however. To investigate the impact of recurrent nocturnal hypoxia on hemodynamics, sympathetic activity, and vascular tone we evaluated 10 normal volunteers before and after 14 nights of nocturnal sustained hypoxia (mean oxygen saturation 84.2%, 9 h/night). Over the exposure, subjects exhibited ventilatory acclimatization to hypoxia as evidenced by an increase in resting ventilation (arterial Pco(2) 41.8 +/- 1.5 vs. 37.5 +/- 1.3 mmHg, mean +/- SD; P < 0.05) and in the isocapnic hypoxic ventilatory response (slope 0.49 +/- 0.1 vs. 1.32 +/- 0.2 l/min per 1% fall in saturation; P < 0.05). Subjects exhibited a significant increase in mean arterial pressure (86.7 +/- 6.1 vs. 90.5 +/- 7.6 mmHg; P < 0.001), muscle sympathetic nerve activity (20.8 +/- 2.8 vs. 28.2 +/- 3.3 bursts/min; P < 0.01), and forearm vascular resistance (39.6 +/- 3.5 vs. 47.5 +/- 4.8 mmHg.ml(-1).100 g tissue.min; P < 0.05). Forearm blood flow during acute isocapnic hypoxia was increased after exposure but during selective brachial intra-arterial vascular infusion of the alpha-blocker phentolamine it was unchanged after exposure. Finally, there was a decrease in reactive hyperemia to 15 min of forearm ischemia after the hypoxic exposure. Recurrent nocturnal hypoxia thus increases sympathetic activity and alters peripheral vascular tone. These changes may contribute to the increased cardiovascular and cerebrovascular risk associated with clinical diseases that are associated with chronic recurrent hypoxia.
Authors:
Geoffrey S Gilmartin; Renaud Tamisier; Matthew Curley; J Woodrow Weiss
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2008-06-06
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  295     ISSN:  0363-6135     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2008 Aug 
Date Detail:
Created Date:  2008-08-08     Completed Date:  2008-09-25     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H778-85     Citation Subset:  IM    
Affiliation:
Laboratoire d'Exploration Fonctionnelle Respiratoire, Centre Hospitalier Universitaire de Grenoble BP 217, 38043 Grenoble Cedex 9, France.
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MeSH Terms
Descriptor/Qualifier:
Acclimatization
Adrenergic alpha-Antagonists / administration & dosage
Adult
Anoxia / physiopathology*
Blood Pressure
Circadian Rhythm*
Female
Forearm / blood supply*
Heart Rate
Hemodynamics* / drug effects
Humans
Hyperemia / physiopathology
Infusions, Intra-Arterial
Male
Muscle, Skeletal / innervation*
Phentolamine / administration & dosage
Pulmonary Ventilation*
Regional Blood Flow
Sympathetic Nervous System / physiopathology*
Time Factors
Vascular Resistance*
Grant Support
ID/Acronym/Agency:
HL-072648/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 50-60-2/Phentolamine
Comments/Corrections

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