| WISE-2005: prolongation of left ventricular pre-ejection period with 56 days head-down bed rest in women. | |
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MedLine Citation:
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PMID: 20696784 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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This study tested the hypothesis that prolonged physical deconditioning affects the coupling of left ventricular depolarization to its ejection (the pre-ejection period, PEPi) and that this effect is minimized by exercise countermeasures. Following assignment to non-exercise (Control) and exercise groups (Exercise), 14 females performed 56 days of continuous head-down tilt bed rest. Measurements of the electrocardiogram (ECG) and stroke volume (Doppler ultrasound) during supine rest were obtained at baseline prior to (Pre) and after (Post) the head-down tilt bed rest (HDBR) period. Compared with Pre, the PEPi was increased following head-down tilt bed rest (main effect, P < 0.005). This effect was most dominant in the Control group [Pre = 0.038 ± 0.06 s (s.d.) versus Post = 0.054 ± 0.011 s; P < 0.001]. In the Exercise group, PEPi was 0.032 ± 0.005 s Pre and 0.038 ± 0.018 s Post; P= 0.08. Neither the QRS interval nor cardiac afterload was modified by head-down tilt bed rest in Control or Exercise groups. Low-dose isoprenaline infusion reversed the head-down tilt bed rest-induced delay in the PEPi. These results suggest that head-down tilt bed rest leads to a delayed onset of systolic ejection following left ventricular depolarization in a manner that is affected little by the exercise countermeasure but is related to β-adrenergic pathways. The delayed onset of systole following head-down tilt bed rest appears to be related to mechanism(s) affecting contraction of the left ventricle rather than its depolarization. |
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Authors:
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Gary J Hodges; Louis Mattar; Kathryn A Zuj; Danielle K Greaves; Phillipe M Arbeille; Richard L Hughson; J Kevin Shoemaker |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. |
Journal Detail:
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Title: Experimental physiology Volume: 95 ISSN: 1469-445X ISO Abbreviation: Exp. Physiol. Publication Date: 2010 Nov |
Date Detail:
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Created Date: 2010-10-22 Completed Date: 2011-01-28 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9002940 Medline TA: Exp Physiol Country: England |
Other Details:
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Languages: eng Pagination: 1081-8 Citation Subset: IM |
Affiliation:
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School of Kinesiology, University of Western Ontario, London, Ontario, Canada. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Bed Rest* Blood Pressure / drug effects Cardiovascular Deconditioning* Electrocardiography Female Head-Down Tilt / physiology* Heart Ventricles / drug effects, physiopathology* Humans Isoproterenol / diagnostic use Lower Body Negative Pressure Norepinephrine / diagnostic use Stroke Volume Supine Position Weightlessness Countermeasures Weightlessness Simulation |
| Grant Support | |
ID/Acronym/Agency:
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//Canadian Institutes of Health Research |
| Chemical | |
Reg. No./Substance:
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51-41-2/Norepinephrine; 7683-59-2/Isoproterenol |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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