Document Detail


Consequences of cardiovascular adaptation to spaceflight: implications for the use of pharmacological countermeasures.
MedLine Citation:
PMID:  16038093     Owner:  NASA     Status:  MEDLINE    
Abstract/OtherAbstract:
There is little evidence obtained from space flight to support the notion that occurrence of cardiac dysrhythmias, impaired cardiac and vascular function, and manifestation of asymptomatic cardiovascular disease represent serious risks during space flight. Therefore, the development of orthostatic hypotension and instability immediately after return from spaceflight probably reflect the most significant operational risks associated with the cardiovascular system of astronauts. Significant reductions in stroke volume and lower reserve for increasing peripheral vascular resistance contribute to ineffective maintenance of systemic arterial blood pressure during standing after spaceflight despite compensatory elevations in heart rate. The primary mechanism underlying reduced stroke volume appears to be a reduction in preload associated with less circulating blood volume while inadequate peripheral vasoconstriction may be caused partly by hyporeactivity of receptors that control arterial smooth muscle function. A focus for development of future countermeasures for hemodynamic responses to central hypovolemia includes the potential application of pharmacological agents that specifically target and restore blood volume (e.g., fludrocortisone, electrolyte-containing beverages) and reserve for vasoconstriction (e.g., midodrine, vasopressin). Based on systematic evaluations, acute physical exercise designed to elicit maximal effort or inspiratory resistance have shown promise as successful countermeasures that provide protection against development of orthostatic hypotension and intolerance without potential risks and side effects associated with specific pharmacological interventions.
Authors:
Victor A Convertino
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Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  Gravitational and space biology bulletin : publication of the American Society for Gravitational and Space Biology     Volume:  18     ISSN:  1089-988X     ISO Abbreviation:  Gravit Space Biol Bull     Publication Date:  2005 Jun 
Date Detail:
Created Date:  2005-07-24     Completed Date:  2005-10-21     Revised Date:  2009-04-08    
Medline Journal Info:
Nlm Unique ID:  9816128     Medline TA:  Gravit Space Biol Bull     Country:  United States    
Other Details:
Languages:  eng     Pagination:  59-69     Citation Subset:  S    
Affiliation:
U.S. Army Institute of Surgical Research, Fort Sam Houston, Texas 78234-6513, USA. victor.convertino@amedd.army.mil
Space Flight Mission:
Flight Experiment; STS Shuttle Project; manned; short duration
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological
Adrenergic alpha-Agonists / therapeutic use
Aerospace Medicine
Astronauts
Blood Pressure / physiology
Blood Volume / physiology
Cardiac Output / physiology
Cardiovascular Deconditioning / drug effects,  physiology
Exercise / physiology
Fludrocortisone / therapeutic use
Hemodynamics / physiology*
Humans
Hypotension, Orthostatic / drug therapy*,  etiology
Midodrine / therapeutic use
Sodium Chloride / therapeutic use
Space Flight*
Stroke Volume / physiology
Vascular Resistance / physiology
Weightlessness / adverse effects*
Weightlessness Countermeasures*
Chemical
Reg. No./Substance:
0/Adrenergic alpha-Agonists; 127-31-1/Fludrocortisone; 42794-76-3/Midodrine; 7647-14-5/Sodium Chloride
Investigator
Investigator/Affiliation:
V A Convertino / US Army Inst Surgical Res, Ft Sam Houston, TX

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


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