Erythropoietin under real and simulated micro-g conditions in
man.
Gunga, Hanns-Christian, Karl Kirsch, Friedrich Baartz, Alain Maillet,
Claude Gharib, Walidimir Nalishiti, Ivan Rich, and Lothar
R[diaeresis]ocker.
Department of Physiology, Free University of Berlin, Arnimallee 22,
D 14 195 Berlin, Germany, Laboratoire de Physiologie de
l'Environment, Facult[acute]e de M[acute]edecine Lyon Grange-Blanche,
8 Avenue Rockefeller, F-69373 Lyon, France, 3ZPK, 14160 Star City,
Moscow, Russia, German Red Cross, University Ulm,
Helmholtzstra[beta]e 10, 89081 Ulm, Germany
APStracts 3:0142A, 1996.
It was the aim of this study 1) to analyze the time course of
erythropoietin during earth-bound micro-g simulations such as bed
-rest, isolation and confinement, head-down tilt (- degrees 6), and
immersion so as to evaluate 2) which factors could contribute to
alterations found in erythropoietin under real micro-g conditions
during and after short- (<10 days) and long-term (>6
months) space-flights. During bed-rest (24 hrs duration, N=10, male)
no significant changes in erythropoietin could be observed. Subjects
(N = 4; 1 female, 3 male) confined in a diving chamber facility for
60 days showed, after 3 weeks inside the chamber, an erythropoietin
decrease until the last week inside the chamber. In the recovery
period a slight increase was observed, but erythropoietin
concentrations did not reach the pre-isolation control level. In the
control period before head-down tilt subjects (N = 8, male) showed
normal resting values for erythropoietin, but already on the 2nd day
of head-down tilt the erythropoietin concentrations were decreased
(P<0.01). During the following weeks the erythropoietin levels
remained below the control value and were increased during the 1st
week post-head-down tilt (P<0.05). After immersion (1hr
duration, N = 8, male) the erythropoietin values were unchanged,
whereas 24 hrs later a significant increase could be determined
(P<0.05). During the German D-2 mission, a short-term space
-flight, the astronauts (N = 4, male) showed pre-flight normal resting
erythropoietin levels (9.3 +/- 2.2 mU . ml-1). In-flight (4th day)
the erythropoietin concentrations were decreased (6.0 +/- 5.1 mU .
ml-1): two astronauts had very low erythropoietin levels (subject A
0.3 mU . ml-1; subject D 3.3 mU . ml-1) while the other ones showed
nearly unchanged concentrations. On the recovery day the
erythropoietin concentrations were slightly further decreased (5.6
+/- 3.3 mU . ml-1) and increased slowly towards control level in the
post-flight phase (7th day 7.4 +/- 3.4 mU . ml-1; 15th day 10.9 +/-
2.1 mU . ml-1). During the Euromir'94-e mission, a long-term space
-flight, the cosmonaut (N = 1, male) showed pre-flight normal resting
erythropoietin levels (14.4 mU . ml-1). One day after the recovery
the erythropoietin concentration was slightly elevated, but in the
normal range (19.4 mU . ml-1). In the following post-flight phase the
erythropoietin values increased markedly (2nd day 46.3 mU . ml-1) and
remained elevated (5th day 43.1 mU . ml-1). It is concluded that 1)
head-down tilt (- degrees 6) causes a rapid erythropoietin decrease
in man; 2) isolation and confinement per se lead to diminished
erythropoietin concentrations; 3) during a short-duration spaceflight
(<10 days) extremely low erythropoietin concentrations were
observed in-flight in two out of four astronauts, whereas in the
other ones unchanged erythropoietin concentrations were determined.
After two weeks post-flight all subjects showed normal erythropoietin
concentration; 4) increased erythropoietin concentrations above
control range were found immediately after long-term space flights;
5) changes in central blood volume, i.e. central venous pressure,
might be involved in the modulation of erythropoietin production and
release under simulated and real micro-g conditions; and 6) the head
-down tilt (- degrees 6) earth-bound simulation reflects most likely
the changes in erythropoietin production and release observed under
micro-g conditions in man.
Received 18 September 1995; accepted in final form 4 March 1996.
APS Manuscript Number A1014-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96