12 Vivarium, 12 Synchronous
Key Flight Hardware
Cosmos 782 Russian Hardware Suite
Objectives/Hypothesis
If bones are formed in relation to gravitational stresses, one would anticipate
that prolonged recumbency and/or prolonged weightlessness would be associated
with hypercalciuria, bone demineralization, and osteoporosis. To better understand
the effect of space flight on bone, parameters including formation and mineraliza-
tion, resorption, length, density and pore size distribution, and bone mechanical
properties were studied in rats both immediately postflight and at 25 days post-
flight.
Approach or Method
Bone density and pore size distribution were measured by mercury porosimetry
in the left humerus, while humerus mechanical properties were evaluated with
a standard torsion test machine. Bone formation, mineralization, and resorption
rates were determined by quantitative histological techniques using the left
tibia, while osteoblastic and osteoclastic cell populations were determined
from the right. Length measurements were made with calipers, and correlation,
regres- sion, and covariance analyses were made by means of computer programs
based on standard statistical methods.
Results
Space flight had little effect on the bone porosity parameters measured, while
the flight and synchronous animals (compared to viarium controls) did show a
signifi- cant decrease in bone density immediately postflight. The most striking
effects were those on bone formation; all parameters investigated in the flight
animals immediately after flight were significantly decreased from both vivarium
and synchronous controls. An arrest line was found at both the endosteum and
the periosteum of flight animals suggesting that a complete cessation of bone
growth occurred during the flight. By 25 days postflight, flight animals showed
a signifi- cant increase in formation, suggesting that a rebound in bone formation
had occurred following flight.
Publications
Experiment Reference Number: C782-6
Holton, E.M.: Effects of Weightlessness on Bone and Muscle of Rats. Space
Gerontology, NASA CP-2248, 1982, pp. 59-66.
Morey, E.R. and D.J. Baylink: Inhibition of Bone Formation During Spaceflight.
Science, vol. 201, 1978, pp. 1138-1141.
Morey-Holton, E. and D.J. Baylink: Quantitative Analysis of Selected Bone Parameters:
Final Reports of U.S. Experiments Flown on the Soviet Satellite Cosmos 782.
S.N. Rosenzweig and K.A. Souza, eds., NASA TM-78525, 1978, pp. 321-351.
¥ = publication of related ground-based study