Document Detail

Dynamic adaptation of cardiac baroreflex sensitivity to prolonged exposure to microgravity: data from a 16-day spaceflight.
MedLine Citation:
PMID:  18756008     Owner:  NLM     Status:  MEDLINE    
This study explored the process of arterial baroreflex adaptation to microgravity, starting from the first day of flight, during the 16-day STS-107 Columbia Space Shuttle mission. Continuous blood pressure (BP), ECG, and respiratory frequency were collected in four astronauts on ground (baseline) and during flight at days 0-1, 6-7, and 12-13, both at rest and during moderate exercise (75 W) on a cycle ergometer. Sensitivity of the baroreflex heart rate control (BRS) was assessed by sequence and spectral alpha methods. Baroreflex effectiveness index (BEI); low-frequency (LF) power and high-frequency (HF) power of systolic BP (SBP), diastolic BP (DBP), and R-R interval (RRI); the RRI LF/HF ratio; and the RRI root mean square of successive differences (RMSSD) index were also estimated. We found that, at rest, BRS increased in early flight phase, compared with baseline (means +/- SE: 18.3 +/- 3.4 vs. 10.4 +/- 1.2 ms/mmHg; P < 0.05), and it tended to return to baseline in subsequent days. During exercise, BRS was lower than at rest, without differences between preflight and in-flight values. At rest, in the early flight phase, RMSSD and RRI HF power increased (P < 0.05) compared with baseline, whereas LF powers of SBP and DBP decreased. No statistical difference was found in these parameters during exercise before vs. during flight. These findings demonstrate that heart rate baroreflex sensitivity and markers of cardiac vagal modulation are enhanced during early exposure to microgravity, likely because of the blood centralization, and return to baseline values in subsequent flight phases, possibly because of the fluid loss. No deconditioning seems to occur in the baroreflex control of the heart.
M Di Rienzo; P Castiglioni; F Iellamo; M Volterrani; M Pagani; G Mancia; J M Karemaker; G Parati
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-08-28
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  105     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2008 Nov 
Date Detail:
Created Date:  2008-11-05     Completed Date:  2008-12-04     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1569-75     Citation Subset:  IM    
Polo Tecnologico, Fondazione Don Carlo Gnocchi, ONLUS Via Capecelatro 66, 20133 Milano, Italy.
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MeSH Terms
Adaptation, Physiological
Blood Pressure*
Cardiovascular System / innervation*
Exercise / physiology*
Heart Rate*
Middle Aged
Respiratory Mechanics
Space Flight*
Time Factors
Vagus Nerve / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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