| WISE-2005: adrenergic responses of women following 56-days, 6 degrees head-down bed rest with or without exercise countermeasures. | |
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MedLine Citation:
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PMID: 17928515 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We tested the hypotheses that women completing 56 days, 6 degrees head-down bed-rest (HDBR) would have changes in sensitivity of cardiovascular responses to adrenergic receptor stimulation and that frequent aerobic and resistive exercise would prevent these changes. Twenty-four women, eight controls, eight exercisers (lower body negative pressure treadmill and flywheel resistance exercise), and eight receiving nutritional supplement but no exercise were studied in baseline and during administration of the beta-agonist isoproterenol (ISO) and the alpha- and beta-agonist norepinephrine (NOR). In the control and nutrition groups, HDBR increased heart rate (HR) and reduced stroke volume (SV), and there was a significantly greater increase in HR with ISO after HDBR. In contrast, the HR and SV of the exercise group were unchanged from pre-HDBR. After HDBR, leg vascular resistance (LVR) was greater than pre-HDBR in the exercise group but reduced in control and nutrition. LVR was reduced with ISO and increased with NOR. Changes in total peripheral resistance were similar to those of LVR but of smaller magnitude, perhaps because changes in cerebrovascular resistance index were directionally opposite to those of LVR. There were no changes in sensitivity of the vascular resistance responses to adrenergic stimulation. The HR response might reflect a change in sensitivity or a necessary response to the reduction in SV after HDBR in control and nutrition groups. The reduced peripheral vascular resistance after HDBR might help to explain orthostatic intolerance in women. Exercise was an effective countermeasure to the HDBR effects. |
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Authors:
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Heather Edgell; Kathryn A Zuj; Danielle K Greaves; J Kevin Shoemaker; Marc-Antoine Custaud; Pascaline Kerbeci; Phillipe Arbeille; Richard L Hughson |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2007-10-10 |
Journal Detail:
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Title: American journal of physiology. Regulatory, integrative and comparative physiology Volume: 293 ISSN: 0363-6119 ISO Abbreviation: Am. J. Physiol. Regul. Integr. Comp. Physiol. Publication Date: 2007 Dec |
Date Detail:
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Created Date: 2007-12-06 Completed Date: 2008-02-15 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 100901230 Medline TA: Am J Physiol Regul Integr Comp Physiol Country: United States |
Other Details:
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Languages: eng Pagination: R2343-52 Citation Subset: IM |
Affiliation:
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Faculty of Applied Health Sciences, Rm. 3116, Burt Matthews Hall, Univ. of Waterloo, Waterloo, ON, Canada, N2L 3G1. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adaptation, Physiological
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physiology* Adult Bed Rest / methods* Exercise / physiology* Female Head-Down Tilt / physiology* Heart Rate / physiology Humans Norepinephrine / metabolism Physical Exertion / physiology* Receptors, Adrenergic / metabolism* Rest / physiology* Stroke Volume / physiology |
| Chemical | |
Reg. No./Substance:
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0/Receptors, Adrenergic; 51-41-2/Norepinephrine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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