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Gender Differences in Bed Rest: Preliminary Analysis of Vascular FunctionOrthostatic intolerance is a recognized consequence of spaceflight. Numerous studies have shown that women are more susceptible to orthostatic intolerance following spaceflight as well as bed rest, the most commonly used ground-based analog for spaceflight. One of the possible mechanisms proposed to account for this is a difference in vascular responsiveness between genders. We hypothesized that women and men would have differing vascular responses to 90 days of 6-degree head down tilt bed rest. Additionally, we hypothesized that vessels in the upper and lower body would respond differently, as has been shown in the animal literature. Thirteen subjects were placed in bedrest for 90 days (8 men, 5 women) at the Flight Analogs Unit, UTMB. Direct arterial and venous measurements were made with ultrasound to evaluate changes in vascular structure and function. Arterial function was assessed, in the arm and leg, during a reactive hyperemia protocol and during sublingual nitroglycerin administration to gauge the contributions of endothelial dependent and independent dilator function respectively. Venous function was assessed in dorsal hand and foot veins during the administration of pharmaceuticals to assess constrictor and dilator function. Both gender and day effects are seen in arterial dilator function to reactive hyperemia, but none are seen with nitroglycerin. There are also differences in the wall thickness in the arm vs the leg during bed rest, which return toward pre-bed rest levels by day 90. More subjects are required, especially females as there is not sufficient power to properly analyze venous function. Day 90 data are most underpowered.
Document ID
20080010876
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Platts, Steven H.
(NASA Johnson Space Center Houston, TX, United States)
Stenger, Michael B.
(Wyle Labs., Inc. Houston, TX, United States)
Martin, David S.
(Wyle Labs., Inc. Houston, TX, United States)
Freeman-Perez, Sondra A.
(Wyle Labs., Inc. Houston, TX, United States)
Phillips, Tiffany
(Wyle Labs., Inc. Houston, TX, United States)
Ribeiro, L. Christine
(Wyle Labs., Inc. Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
February 4, 2008
Subject Category
Aerospace Medicine
Meeting Information
Meeting: Human Research Program Investigators'' Workshop
Location: League City, TX
Country: United States
Start Date: February 4, 2008
End Date: February 6, 2008
Distribution Limits
Public
Copyright
Public Use Permitted.
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