Control of the red blood cell mass in spaceflight.
Alfrey, Clarence P., Mark M. Udden, Carolyn Leach Huntoon, Theda
Driscoll, Mark H. Pickett.
Department of Medicine, Baylor College of Medicine, Gulf Coast
Regional Blood Center and the NASAJohnson Space Center, Houston,
Texas
APStracts 2:0374A, 1995.
The effect of spaceflight on red blood cell mass (RBCM), plasma volume
(PV), erythron iron turnover, serum erythropoietin, red blood cell
(RBC) production, survival and indices were determined for six
astronauts on two shuttle missions, 9 and 14 days in duration. PV
decreased within the first day. The RBCM decreased because of
destruction of RBCs either newly released or scheduled to be released
from the bone marrow. Older RBCs survived normally. Upon return to
earth, plasma volume increased, hemoglobin concentration and RBC
count declined and serum erythropoietin increased. We propose that
entry into microgravity results in acute plethora as a result of a
decrease in vascular space. PV decreases causing an increase in
hemoglobin concentration which effects a decrease in erythropoietin
or other growth factors or cytokines. The RBCM decreases by
destruction of recently formed RBCs to a level appropriate for the
microgravity environment. Return to earth results sequentially in
acute hypovolemia as vascular space dependent upon gravity is
refilled, an increase in plasma volume, a decrease in hemoglobin
concentration (anemia) and an increase in serum erythropoietin.
Received 23 December 1994; accepted in final form 8 August 1995.
APS Manuscript Number A1307-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 15 September 1995.