[Prophylaxis of the unfavorable shifts in mineral turnover in bones during extended exposure to the conditions reproducing the physiological effects of microgravity].

Effectiveness of the countermeasures and methods for mitigation of the unfavorable effects of microgravity on mineral turnover and properties of bones was evaluated in simulation experiments with animals (penal immobilization, suspension) and with participation of human subjects (37 to 120-d head-down bed rest). The experiments with rats were aimed at testing pharmaceutical preparations (bisphosphonates), determining doses, plan and way of administration. Preparations of this group differ considerably in their action on osteogenesis, mostly because of specifics of the chemical structure. Nonetheless, optimization of the course of treatment masked significantly side effects without detriment to the preventive action. Head-down bed rest was used to test effectiveness of physical exercises (PE) as a main countermeasure against the microgravity impacts. Both standard and experimental PE regimens were tested. Several groups of test-subjects combined PE with consumption of xidifon (a bisphosphonate). In addition, mineral supplements (potassium and calcium) were used. The PE + xidifon combination and regulation of mineral intake with foods was found to reduce calcium losses during 370-d bed rest and prevent a material degradation of strength of bone samples, and essentially rehabilitate shifts in the hormonal regulation of calcium turnover and calciuretic function of the kidney.