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Leg vascular responsiveness during acute orthostasis following simulated weightlessnessThe effect of weightlessness on vascular response to orthostatic stress was investigated in human subjects by measuring changes in the arterial pulse volume (APV) of the legs during exposure to lower body negative pressure (LBNP) applied before and after 10 days of continuous 6-deg head-down bed rest. Heart rate, mean arterial blood pressure (MAP), and impedance rheographic indices of APV were measured during rest and at 1 min of -30 mm Hg LBNP. Bed rest was found not to alter the responses of MAP to LBNP. Resting APV was decreased after bed rest; however, APV was reduced upon transfer from rest to 1-min LBPN by the same relative magnitude before and after bedrest. It is concluded that peripheral arterial vasoconstriction, as indicated by reduction in APV during LBNP, is not affected by bedrest. The results suggest that there was no apparent alteration in responsiveness of the leg vasculature following simulated weightlessness, and that the control mechanisms of peripheral resistance do not contribute significantly to reduced orthostatic tolerance following spaceflight.
Document ID
19880037316
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Blamick, Cynthia A.
(NASA John F. Kennedy Space Center Cocoa Beach, FL, United States)
Goldwater, Danielle
(NASA John F. Kennedy Space Center Cocoa Beach, FL, United States)
Convertino, Victor A.
(NASA Kennedy Space Center; Bionetics Corp., Cocoa Beach, FL; NASA, Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 13, 2013
Publication Date
January 1, 1988
Publication Information
Publication: Aviation, Space, and Environmental Medicine
Volume: 59
ISSN: 0095-6562
Subject Category
Aerospace Medicine
Accession Number
88A24543
Funding Number(s)
CONTRACT_GRANT: NCA2-OR-745-911
Distribution Limits
Public
Copyright
Other

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