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Correlation of macro and micro cardiovascular function during weightlessness and simulated weightlessnessThe investigation of cardiovascular function necessarily involves a consideration of the exchange of substances at the capillary. If cardiovascular function is compromised or in any way altered during exposure to zero gravity in space, then it stands to reason that microvascular function is also modified. We have shown that an increase in cardiac output similar to that reported during simulated weightlessness is associated with a doubling of the number of post-capillary venules and a reduction in the number of arterioles by 35%. If the weightlessness of space travel produces similar changes in cardiopulmonary volume and cardiac output, a reasonable expectation is that astronauts will undergo venous neovascularization. We have developed an animal model in which to correlate microvascular and systemic cardiovascular function. The microcirculatory preparation consists of a lightweight, thermo-neutral chamber implanted around intact skeletal muscle on the back of a rat. Using this technique, the performed microvasculature of the cutaneous maximus muscle may be observed in the conscious, unanesthetized animal. Microcirculatory variables which may be obtained include venular and arteriolar numbers, lengths and diameters, single vessel flow velocities, vasomotion, capillary hematocrit anastomoses and orders of branching. Systemic hemodynamic monitoring of cardiac output by electromagnetic flowmetry, and arterial and venous pressures allows correlation of macro- and microcirculatory changes at the same time, in the same animal. Observed and calculated hemodynamic variables also include pulse pressure, heart rate, stroke volume, total peripheral resistance, aortic compliance, minute work, peak aortic flow velocity and systolic time interval. In this manner, an integrated assessment of total cardiovascular function may be obtained in the same animal without the complicating influence of anesthetics.
Document ID
20040112149
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Hutchins, P. M.
(Wake Forest University Medical Center Winston-Salem, NC 27103)
Marshburn, T. H.
Smith, T. L.
Osborne, S. W.
Lynch, C. D.
Moultsby, S. J.
Date Acquired
August 21, 2013
Publication Date
January 1, 1988
Publication Information
Publication: Acta astronautica
Volume: 17
Issue: 2
ISSN: 0094-5765
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: HL-13936
CONTRACT_GRANT: HL-31151
CONTRACT_GRANT: NAS2-10523
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Number 00-00
NASA Discipline Cardiopulmonary
NASA Program Flight
Non-NASA Center

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