[Evaluation of effectiveness of short-term orthostatic positioning of head-down tilted primates on the liquid body sectors].

Head-down tilting (HDT) of primates is a well-recognized model for studying the hypokinetic syndrome effects on the body functions. Benefits for the body liquids distribution of periodic transition of primates (rhesus macaques) into the vertical position without support loading were evaluated in a 30-d HDT experiment. Brief (30 to 120 minutes long, 4-5 times a week) transition from tilting into the vertical position had no influence on primates' hydration homeostasis and its infrastructure.

[Body fluids ratio and postural stability of head-down tilted apes in the periods of transition into the active vertical position].

It is known that the hypokinetic syndrome and alteration of the hydrostatic component by microgravity distort functioning of various body systems. Prevention of the adverse effects is achieved through implementation of a variety of physical exercises during tilting, and periodic transition into the upright position. The investigation was performed with 11 Macaques (Macaca mulatta) 3 to 5 yrs.

Mechanisms of the decrease in human postural stability during prolonged head-down tilt.

In 3 identical experiments with head-down bed rest lasting 60, 90, and 120 days and involving 18 volunteers, dynamics of the development of cardiovascular system (C.V.S) deconditioning was studied.

Physiological reactions of primates to 9-D immersion and head-down tilt.

Purpose of the investigation was to compare physiological reactions of primates (Macaca mulatta) to microgravity simulated by immersion and head-down tilt (HDT). In immersion experiments, primates in waterproof suits were put into motion-restraining chairs and immersed into water (t=35.4 degrees C) breast-deep for 9 days.

[Prevention of the adverse effects of head-down tilting on the infrastructure of body fluids and postural stability of primates by exposure to g-loads].

Experiments with 24 primates (Macaca mulatta) demonstrated that head-down tilting (-5 degrees) altered their hydration status as was manifested by a significant diminution of the amount of extracellular fluids, the interstitial fraction specifically. Blood circulation in leg muscles reduced almost in half In addition, return of the animals to the orthostatic position at the end of the experiment did not cause so intensive blood redistribution in leg vessels as in the group of tilted but not rotated animals.