[Vertebral, femoral and radial bone density in simulation of prolonged weightlessness. Experience with healthy volunteers].
Disturbances in bone tissue induced by weightlessness in man are incompletely known. All we possess are indirect data which show negativation of the calcium-phosphate balance and bone density measurements mainly in peripheral bones (calcaneum and radius bones). Staying in supine position with the head down (the so-called anti-orthostatic position) is a means of simulating on earth the effects of weightlessness in space flights. We studied the changes in vertebral, femoral and radial bone densities that might occur in 7 healthy volunteers subjected to two 1-month period of bed rest with strict (-6 degrees) anti-orthostatic position. No significant variation was recorded at the end of each period. When the two periods were added the mean vertebral bone loss was -0.9 percent per month. This figure was comparable to that found in similar studies performed in the USA with longer periods of bed rest. The bone loss in such experiments was 4 to 8 times less than that reported for pathological immobilization. Further simulation studies are needed to evaluate the bone loss kinetics and to test the effectiveness of the preventive measures used in spatial flights.
Pouilles
J M
JM
Service d'Endocrinologie, CHU Purpan, Toulouse.
Ribot
C
C
Trémollières
F
F
Guell
A
A
D000328:Adult; D015519:Bone Density / Q000502:physiology*; D005269:Femur / Q000502:physiology*; D006801:Humans; D007103:Immobilization / Q000009:adverse effects; D008159:Lumbar Vertebrae / Q000502:physiology*; D008297:Male; D011884:Radius / Q000502:physiology*; D012016:Reference Values; D013997:Time Factors; D014893:Weightlessness / Q000009:adverse effects*
Densité osseuse vertébrale, fémorale et radiale au cours d'une simulation d'apesanteur de longue durée. Expérience chez des volontaires sains.