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NASA
Technical
Memorandum
108800
Intermittent Gravity: How Much, How Often, How Long? Joan Vernikos and David A. Ludwig
(NASA-TM-I08800) GRAVITY: HOW LONG? (NASA)
MUCH, 106
INTERMITTENT HOW OFTEN, p
N94-26098 HOW Unclas
G3/55
January
1994
#
7
NASA National Aeronautics and Space Administration
i
0209002
|
NASA Technical
Memorandum
108800
Intermittent Gravity: How Much, How Often, How Long? Joan Vernikos,
Ames Research
David A. Ludwig,
January
University
Center,
Moffett
of North Carolina,
1994
National Aeronautics and Space Administration Ames Research Center Moffett Field, California 94035-1000
Field, California Greensboro,
North Carolina
,f
Table
of Contents Page
Preface ................................................................................................................................................................. Glossary
...............................................................................................................................................................
Summary
..............................................................................................................................................................
Introduction Methods
vii
.......................................................................................................................................................... 3 3 4 4 4 4 5 5 5 5 6 6 7
...............................................................................................................................................................
Subjects ........................................................................................................................................................ Table 1. Control data from tests before HDBR exposures .............................................................. Treatments and Experimental Protocol ........................................................................................................ Table 2. Five treatment conditions .................................................................................................. Experimental Conditions .............................................................................................................................. Experimental Procedures .............................................................................................................................. Blood Samples .............................................................................................................................................. Urine Samples .............................................................................................................................................. Tilt Tolerance Test ....................................................................................................................................... Peak Oxygen Consumption Test .................................................................................................................. Plasma Volume ............................................................................................................................................ Blood Analyses ............................................................................................................................................ Urine Analyses ............................................................................................................................................. Statistics ........................................................................................................................................................ Statistics: orthostatic tolerance .............................................................................................................. Results .................................................................................................................................................................. Orthostatic Tolerance: Heart Rate and Blood Pressure ................................................................................ Figure I. Heart rate response to 60 ° head-up tilt by treatment conditions ........................................ Figure 2. Mean arterial pressure response to 60 ° head-up tilt by treatment conditions .................... Figure 3. Systolic blood pressure response to 60 ° head-up tilt by treatment conditions .................. Figure 4. Diastolic blood pressure response to 60 ° head-up tilt by treatment conditions ................ Heart Rate Responses ............................................................................................................................ Mean Arterial Pressure Responses ........................................................................................................ Systolic Blood Pressure and Diastolic Blood Pressure Responses ....................................................... Orthostatic Tolerance: Syncope Prevalence .......................................................................................... Figure 5. Tilt test survival rates by treatment conditions for pre- and post-HDBR measurements.. Peak Oxygen Consumption ....................................... .................................................................................... Figure 6. Pre- to post-HDBR differences in VO2pea k ............................................................................ Plasma Volume ............................................................................................................................................ Figure 7. Pre- to post-HDBR differences in plasma volume ............................................................ Urinary Calcium ........................................................................................................................................... Figure 8. Actual and predicted urinary calcium by treatment conditions and HDBR days .............. Figure 9. Linear change in urinary calcium by treatment conditions during HDBR ........................ Figure 10. Quadratic change in urinary calcium by treatment conditions during HDBR .................. Conclusions
w,_¢
Summary
of results ............................................................................................................
References
.....................................................................
Appendix:
Data Tables
_ "__
21 21
..........................................................................................................................................................
Table 3.
_............................................................................
_.........
........................................................................................................................................
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8 8 9 10 II 12 13 13 13 13 14 15 16 15 17 15 18 19 20
22 25
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pr_,.,,-
Preface This technical
memorandum
is a compilation
of the results of a 4-day head-down
bed rest (HDBR)
study. This study was
designed to investigate the effects of 4 days of HDBR alone or with 2 or 4 hours of standing or walking intermittently during each day of HDBR on orthostatic tolerance, maintenance of working capacity (peak oxygen uptake), calcium excretion, and endocrine and fluid and electrolyte responses. The following investigators participated: A. C. Ertl, Ph.D., C. E. Wade, Ph.D., L. Keil, Ph.D., J. E. Greenleaf, Ph.D., and D. O'Hara, R.N., NASA Ames Research Center, Moffett Field, CA 94035-1000. In addition, M. R. Duvoisin, Ph.D., and J. L. Stinn, Ph.D., Biomedical Operations and Research Office, NASA Kennedy Space Center, FL 32899, were instrumental in developing the software for the monitoring and recording of continuous cardiovascular data during the orthostatic tests and St. J. Maloney and V. Reyna for data analyses and compilation of this document. Portions of this report were funded by NASA Ames Research Center Consortium Agreement #NCA2-629. Joan Vernikos,
Ph.D.
Chief (Acting) Life Science Division NASA Ames Research Moffett
Field,
Center
California
David A. Ludwig, Ph.D. Associate Professor of Mathematics and Statistics University of North Carolina Greensboro, North Carolina
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2
Glossary
HR
heart rate
ANCOVA
analysis
of covariance
HRF
Human
ANOVA
analysis
of variance
ISE
ion specific
ANP
atrial natriuretic
K
potassium
APA
alkaline
picric acid
LBNP
lower body negative
AVP
arginine
vasopressin
LDL
low density lipoprotein
BP
blood pressure
MAP
mean arterial pressure
bpm
beats per minute
Na
sodium
BR
bed rest
NE
norepinephrine
BV
blood volume
NF
non-fainter
during
C
ambulatory
P
probability
value
PRA
plasma
renin activity
PV
plasma
volume
RIA
radioimmunoassay
S
standing condition for 4 hours)
SBP
systolic
SD
standard
deviation
SE
standard
error
VO2pea k
peak oxygen
W
walking condition for 4 hours)
peptide
control
Ca
calcium
DBP
diastolic
E
epinephrine
F
fainter during
G
gravity
Gz
gravity
GFR
glomerular
Hct
hematocrit
HDBR
head-down
HDL
high density lipoprotein
blood pressure
tilt test
in head-to-toe filtration
Research
Facility
electrode
pressure
tilt test
(e.g., $4, standing
blood pressure
vector rate
bed rest
consumption (e.g., W4, walking
r
