Effect of short-term microgravity and long-term hindlimb unloading on rat cardiac
mass and function.
Ray, Chester A., Marilyn Vasques, Todd A. Miller, M. Keith Wilkerson, and Michael D.
Delp.
1Departments of Medicine and Cellular and Molecular Physiology, Pennsylvania
State University College of Medicine Hershey, Pennsylvania 17033; 2Life Sciences
Division, «nasa» Ames Research Center, Moffett Field, California 94035; and
3Department of Health and Kinesiology, Texas A&M University, and 4Department
of Medical Physiology, and the Cardiovascular Research Institute, Texas A&M
Health Science Center, College Station, Texas 77843
APStracts 8:0319A, 2001.
The purpose of this study was to test the hypothesis that exposure to short-term
microgravity or long-term hindlimb unloading induces cardiac atrophy in male Sprague-
Dawley rats. For the microgravity study, rats were subdivided into four groups: preflight
(PF, n = 12); flight (Fl, n = 7); flight cage simulation (Sim, n = 6), and vivarium control
(Viv, n = 7). Animals in the Fl group were exposed to 7 days of microgravity during the
Spacelab 3 mission. Animals in the hindlimb-unloading study were subdivided into three
groups: control (Con, n = 20), 7-day hindlimb-unloaded (7HU, n = 10), and 28-day
hindlimb-unloaded (28HU, n = 19). Heart mass was unchanged in adult animals exposed
to 7 days of actual microgravity (PF 1.33 ± 0.03 g; Fl 1.32 ± 0.02 g; Sim 1.28 ± 0.04 g;
Viv 1.35 ± 0.04 g). Similarly, heart mass was unaltered with hindlimb unloading (Con
1.40 ± 0.04 g; 7HU 1.35 ± 0.06 g; 28HU 1.42 ± 0.03 g). Hindlimb unloading also had no
effect on the peak rate of rise in left ventricular pressure, an estimate of myocardial
contractility (Con 8,055 ± 385 mmHg/s; 28HU 8,545 ± 755 mmHg/s). These data suggest
that cardiac atrophy does not occur after short-term exposure to microgravity and that
neither short- nor long-term simulated microgravity alter cardiac mass or function.
Received 26 April 2001; accepted in final form 23 May 2001
APS Manuscript Number A215-1.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 29 June 2001