[Ultrasonic studies and calcium content of the bones in experimental animals during limited mobility and weightlessness].

The velocity of ultrasonic propagation, calcium content, and femur size of rats exposed to actual and simulated weightlessness were investigated. The exposure slowed down the ultrasonic velocity in bones. The effect of the calcium content on the ultrasonic velocity in various bone sites was different: as a rule, there was a positive correlation in diaphyses and a negative correlation in epiphyses. These specific features should be taken into consideration when new methods of bone ultrasonic diagnostics will be developed.