Short-Term
Dynamics of Relative Coordination between
Respiratory Movements, Heart Rate and Arterial
Pressure Fluctuations within the Respiratory
Frequency Range
A. RÖSSLER1, V. NOSKOV2,
Z. LÁSZLÓ1, V.V. POLYAKOW2,
H. G. HINGHOFER-SZALKAY3
1Physiological
Institute, School of Medicine,
Karl-Franzens-University Graz, Austria, 2Institute
for Medical-Biological Problems, Moscow, Russia, 3Institute
for Adaptational and Space Flight Physiology,
Austrian Society for Aerospace Medicine Graz,
Austria
Received
November 18, 1999
Accepted July 4, 2000
Summary
The
purpose of this study was to investigate plasma
concentrations of cyclic guanosine monophosphate
(cGMP) and atrial natriuretic peptide (ANP)
during and after real and simulated space flight.
Venous blood was obtained 3 min after the
beginning and 2 min after the lower body negative
pressure maneuver in two cosmonauts preflight
(supine), inflight, and postflight (supine) and
in five other subjects before, at the end, and 4
days after a 5-day head-down tilt (-6°) bed
rest. In cosmonaut 1 (10 days in space), plasma
cGMP fell from preflight 4.3 to 1.4 nM on flight
day 6, and was 3.0 nM on the fourth day after
landing. In cosmonaut 2 (438 days in space), it
fell from preflight 4.9 to 0.5 nM on on flight
day 3, and stayed <0.1 nM with 5, 9, and 14
months in space, as well as on the fourth day
after landing. Three months after the flight his
plasma cGMP was back to normal (6.3 nM).
Cosmonaut 2 also displayed relatively low
inflight ANP values but returned to preflight
level immediately after landing. In a
ground-based simulation on five other persons,
supine plasma cGMP was reduced by an average of
30 % within 5 days of 6° head-down tilt bed
rest. The data consistently demonstrate lowered
plasma cGMP with real and simulated
weightlessness, and a complete disappearance of
cGMP from plasma during, and shortly after
long-duration space flight.
Key
words
Long-duration
space flight · Head-down tilt · Cyclic
guanosine monophosphate · Atrial natriuretic
peptide · Bed rest
Reprint
requests
Andreas
Rössler, Department of Physiology, School of
Medicine, Karl-Franzens-University, Harrachgasse
21, A-8010 Graz, Austria, e-mail: roessler@kfunigraz.ac.at
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