Volozhin A I, Didenko I E, Stupakov G P
Kosm Biol Aviakosm Med. 1981 Jan-Feb;15(1):43-4.
Hypokinesia of 20--42 days lead to a decrease of Ca content and increase of K and Na content in the mineral component of human vertebrae, the Mg and P content remaining unchanged. It is suggested that these changes resulted from shifts in ion metabolism on the surface of hydroxylapatite crystals as well as from increase in the content of calcium phosphate amorphous component. The hypokinesia did not cause chemical changes in the inorganic component of os calcis, probably, due to the low metabolic activity of its microstructures. After hypokinetic exposure the mineral density of vertebrae and os calcis did not differ from the control value, i. e. no osteoporosis was seen.
