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Baroreflex Responses to Acute Changes in Blood Volume in HumansTo test the hypothesis that acute changes in plasma volume affect the stimulus-response relations of high- and low- pressure baroreflexes, eight men (27-44 yr old) underwent measurements for carotid-cardiac and cardiopulmonary baro-reflex responses under the following three volemic conditions: hypovolemic, normovolemic, and hypervolemic. The stimulus- response relation of the carotid-cardiac response curve was generated using a neck cuff device, which delivered pressure changes between +40 and -65 mmHg in continuous steps of 15 mmHg. The stimulus-response relationship, of the cardio-pulmonary baroreflex were studied by measurements of Forearm Vascular Resistance (FVR) and Peripheral Venous Pressure (PVP) during low levels of lower body negative pressure (O to -20 mmHg). The results indicate greater demand for vasoconstriction for equal reductions in venous pressure during progressive hypovolemia; this condition may compromise the capacity to provide adequate peripheral resistance during severe orthostatic stress. Fluid loading before reentry after spaceflight may act to restore vasoconstrictive capacity of the cardiopulmonary baroreflex but may not be an effective countermeasure against potential post- flight impairment of the carotid-cardiac baroreflex.
Document ID
19970016830
Document Type
Reprint (Version printed in journal)
Authors
Thompson, Cynthia A. (NASA Kennedy Space Center Cocoa Beach, FL United States)
Tatro, Dana L. (NASA Kennedy Space Center Cocoa Beach, FL United States)
Ludwig, David A. (North Carolina Univ. Greensboro, NC United States)
Convertino, Victor A. (NASA Kennedy Space Center Cocoa Beach, FL United States)
Date Acquired
August 17, 2013
Publication Date
May 11, 1990
Publication Information
Publication: Baroflex Responses and Blood Volume
ISSN: 0363-6119
Subject Category
Aerospace Medicine
Report/Patent Number
NASA-TM-112456
NAS 1.15:112456
Distribution Limits
Public
Copyright
Public Use Permitted.
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