NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Altered thermoregulatory responses after 15 days of head-down tiltTo determine whether extended exposure to a simulation of microgravity alters thermoregulatory reflex control of skin blood flow, six adult males were exposed to 15 days of 6 deg head-down tilt (HDT). On an ambulatory control day before HDT exposure and on HDT day 15 the core temperature of each subject was increased by 0.5 - 1.0 C by whole body heating with a water-perfused suit. Mean skin temperature, oral temperature (T (sub or)), mean arterial pressure, and forearm blood flow were measured throughout the protocol. Forearm vascular conductance (FVC) was calculated from the ratio of forearm blood flow to mean arterial pressure. After HDT exposure, the T(sub or) threshold at which reflex thermally induced increases in FVC began was elevated, whereas the slope of the T(sub or)-FVC relationship after this threshold was reduced. Moreover, normothermic FVC and FVC at the highest common T(sub or) between pre- and post-HDT trials were reduced after HDT. These data suggest that HDT exposure reduces thermoregulatory responses to heat stress. The mechanisms resulting in such an impaired thermoregulatory response are unknown but are likely related to the relative dehydration that accompanies this exposure.
Document ID
19950042763
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Crandall, Craig G.
(Texas Coll. of Osteopathic Medicine, Fort Worth, TX United States)
Johnson, John M.
(Texas Univ. Health Science Center San Antonio, TX, United States)
Convertino, Victor A.
(Physiology Research Branch, Clinical Science Div., Brooks AF Base, TX United States)
Raven, Peter B.
(NASA Kennedy Space Center Cocoa Beach, FL, United States)
Engelke, Keith A.
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 16, 2013
Publication Date
October 1, 1994
Publication Information
Publication: Journal of Applied Physiology
Volume: 77
Issue: 4
ISSN: 8750-7587
Subject Category
Life Sciences (General)
Accession Number
95A74362
Funding Number(s)
CONTRACT_GRANT: NAS10-10285
CONTRACT_GRANT: NGT-50751
CONTRACT_GRANT: NAS9-611
CONTRACT_GRANT: NIH-HL-08861
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available