Vertebral growth disturbance in rapidly growing rats during 14 days
of spaceflight.
Kitajima, Isao, Ichiro Semba, Takenori Noikura, Kazunori Kawano,
Youichiro Iwashita, Ikuko Takasaki, Ikuro Maruyama, Hiroyuki Arikawa,
Katsuichiro Inoue, Naoyuki Shinohara, Shunji Nagaoka, and Yoshinobu
Ohira.
Department of Laboratory Medicine, Kagoshima University, Department
of Oral Pathology, Kagoshima University, Department of Oral
Radiology, Kagoshima University, Department of Dental Materials
Science, Kagoshima University, Department of Prosthetic Dentistry,
Kagoshima University, Kagoshima, 890, Japan, Space Experimental
Group, National Space Development Agency of Japan, Tsukuba, 305,
Japan, Department of Physiology and Biomechanics, National Institute
of Fitness and Sports, Kanoya, 891-23, Japan
APStracts 2:0353A, 1995.
The effect of 14 days of spaceflight on the vertebrae of rapidly
growing rats was studied. The hardness of the vertebrae was measured
with a Knoop microhardness tester and bone mineral density was
measured from X-ray photographs. Histomorphometric examination was
performed with a microcomputer-aided system. No significant
difference (p>0.05) was observed between spaceflight rats and
ground controls with regard to mechanical hardness or bone mineral
density. However, histological examination revealed irregular
thickening of the endosteal surface of cortical bone in the
spaceflight rats, whereas it was uniform in the ground controls. The
relative area of lamellar bone showed a significant reduction
(p<0.001) in the spaceflight rats. These findings suggest that
the structural disturbances were due to retardation of endosteal
modeling and remodeling. We conclude that delay of vertebral
maturation can occur in rapidly growing rats after even short-term
exposure to microgravity.
Received 23 December 1994; accepted in final form 26 July 1995.
APS Manuscript Number A1315-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 August 1995.