Document Detail

Muscle metaboreflex contribution to cardiovascular regulation during dynamic exercise in microgravity: insights from mission STS-107 of the space shuttle Columbia.
MedLine Citation:
PMID:  16469787     Owner:  NLM     Status:  MEDLINE    
One of the most important features of prolonged weightlessness is a progressive impairment of muscular function with a consequent decrease in exercise capacity. We tested the hypothesis that the impairment in musculo-skeletal function that occurs in microgravity results in a potentiation of the muscle metaboreflex mechanism and also affects baroreflex modulation of heart rate (HR) during exercise. Four astronauts participating in the 16 day Columbia shuttle mission (STS-107) were studied 72-71 days before launch and on days 12-13 in-flight. The protocol consisted of 6 min bicycle exercise at 50% of individual V(o2,max) followed by 4 min of postexercise leg circulatory occlusion (PECO). At rest, systolic (S) and diastolic (D) blood pressure (BP), R-R interval and baroreflex sensitivity (BRS) did not differ significantly between pre- and in-flight measurements. Both pre- and in-flight, SBP increased and R-R interval and BRS decreased during exercise, whereas DBP did not change. During PECO preflight, SBP and DBP were higher than at rest, whereas R-R interval and BRS recovered to resting levels. During PECO in-flight, SBP and DBP were significantly higher whereas R-R interval and BRS remained significantly lower than at rest. The part of the SBP response (delta) that was maintained by PECO was significantly greater during spaceflight than before (34.5 +/- 8.8 versus 13.8 +/- 11.9 mmHg, P = 0.03). The tachycardic response to PECO was also significantly greater during spaceflight than preflight (-141.5 +/- 25.2 versus - 90.5 +/- 33.3 ms, P = 0.02). This study suggests that the muscle metaboreflex is enhanced during dynamic exercise in space and that the potentiation of the muscle metaboreflex affects the vagally mediated arterial baroreflex contribution to HR control.
Ferdinando Iellamo; Marco Di Rienzo; Daniela Lucini; Jacopo M Legramante; Paolo Pizzinelli; Paolo Castiglioni; Fabio Pigozzi; Massimo Pagani; Gianfranco Parati
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of physiology     Volume:  572     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2006 May 
Date Detail:
Created Date:  2006-07-19     Completed Date:  2006-08-08     Revised Date:  2013-06-07    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  829-38     Citation Subset:  IM    
Dipartimento di Medicina Interna, Università di Roma 'Tor Vergata', Roma, Italy.
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MeSH Terms
Adaptation, Physiological / physiology
Baroreflex / physiology*
Blood Pressure / physiology
Exercise / physiology*
Exercise Test
Heart Rate / physiology*
Middle Aged
Muscle, Skeletal / physiology*
Physical Exertion / physiology*
Physical Fitness / physiology
Sample Size
Space Flight*
United States
United States National Aeronautics and Space Administration
Comment In:
J Physiol. 2006 May 1;572(Pt 3):607-8   [PMID:  16543263 ]

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

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