Document Detail

Cardiovascular and hormonal changes with different angles of head-up tilt in men.
MedLine Citation:
PMID:  11300229     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to assess the endocrine status, thoracic impedance, blood concentration, and hemodynamic dose-responses using different angles of passive head-up tilt (HUT) ranging from 12 degrees to 70 degrees in the same subjects. Measurements were performed during 20 min supine position (pre-HUT), 30 min upright (HUT12, HUT30, HUT53, or HUT70), and 20 min supine (post-HUT); subjects 70 min in the supine position only (HUT0) served as resting controls. Norepinephrine increased above resting control values by 19, 44, 80, and 102%; epinephrine by 30, 41, 64, and 68%; aldosterone by 29, 62, 139, and 165%; plasma renin activity n. s., 41, 91, and 89%; vasopressin n.s., 27, 47, and 59%; thoracic bioimpedance n. s., 8, 13, and 16%; heart rate n. s., 5, 26, and 45%, and mean arterial pressure n. s., 5, 7, and 10%; at min 27 of HUT12, HUT30, HUT53, and HUT70, respectively. Pulse pressure decreased with HUT53 and HUT70 by 4 and 10%. Hematocrit increased by 0.2, 1.7, 6.3, and 7.2%, respectively. Blood density increased by 2.3 and 3.0 g/l, plasma density by 1.7 and 1.8 g/l with HUT53 and HUT70. After finishing HUT, heart rate fell to values which stayed below pre-HUT, and also below resting control levels for > or = 5 min ("post-orthostatic bradycardia") even after the lowest orthostatic load (HUT12). Thoracic impedance and arterial pressure remained increased after terminating HUT30, HUT53, and HUT70. In conclusion, passive orthostatic loading of different extent produces specific dose-responses of different magnitude in the endocrine system, blood composition, thoracic impedance, and hemodynamic variables. The heart rate is depressed even after HUT12, while arterial blood pressure and thoracic impedance exceed pre-stimulus levels after greater head-up tilt, indicating altered cardiovascular response after passive orthostasis.
Z László; A Rössler; H G Hinghofer-Szalkay
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Physiological research / Academia Scientiarum Bohemoslovaca     Volume:  50     ISSN:  0862-8408     ISO Abbreviation:  Physiol Res     Publication Date:  2001  
Date Detail:
Created Date:  2001-04-12     Completed Date:  2001-08-02     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9112413     Medline TA:  Physiol Res     Country:  Czech Republic    
Other Details:
Languages:  eng     Pagination:  71-82     Citation Subset:  IM; S    
Department of Physiology, School of Medicine, Karl-Franzens University, Graz, Austria.
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MeSH Terms
Aldosterone / blood
Arginine Vasopressin / blood
Blood Pressure
Blood Volume
Cardiovascular Physiological Phenomena*
Electric Impedance
Epinephrine / blood
Heart Rate
Hormones / blood*
Norepinephrine / blood
Renin / blood
Reg. No./Substance:
0/Hormones; 113-79-1/Arginine Vasopressin; 51-41-2/Norepinephrine; 51-43-4/Epinephrine; 52-39-1/Aldosterone; EC

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