Microgravity decreases heart rate and arterial pressure in
humans.
Fritsch-Yelle, Janice M., John B. Charles, Michele M. Jones, and
Margie L. Wood.
Space Biomedical Research Institute, National Aeronautics and Space
Administration, Johnson Space Center, and KRUG Life Sciences,
Houston, Texas 77058
APStracts 2:0440A, 1995.
Spaceflight causes adaptive changes in cardiovascular physiology that
can have deleterious effects on astronauts, such as postflight
orthostatic intolerance. Inflight cardiovascular data are difficult
to obtain, and results have been inconsistent. To determine normative
inflight changes in Shuttle astronauts, we measured heart rate,
arterial pressure, and cardiac rhythm disturbances for 24 hour
periods before, during, and after spaceflight on Shuttle astronauts
performing their normal routines. We found that heart rate, diastolic
pressure, variability of heart rate and diastolic pressure, and
premature ventricular contractions all were significantly reduced
inflight. Systolic pressure and premature atrial contractions also
tended to be reduced inflight. These data constitute the first
systematic evaluation of inflight changes in basic cardiovascular
variables in Shuttle astronauts, and suggest that a microgravity
environment itself does not present a chronic stress to the
cardiovascular system.
Received 25 May 1995; accepted in final form 26 September 1995.
APS Manuscript Number A550-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95