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In an experiment with 7-d dry immersion for testing the mechanic foot and electrical muscle stimulation procedures of compensating the support load deficiency the following biochemical parameters were studied: activated partial thromboplastin time, prothrombin time, prothrombin index, international normalized ratio, thrombin time (TT), fibrinogen, soluble fibrin-monomer complexes, D-dimer (DD), plasminogen (PG); antithrombin III activity (ATIII), protein C (PC) and alpha2-antiplasmin (AP). Control subjects (immersed w/o stimulation) did not exhibit significant shifts in the hemostasis system: however, they decreased ATIII, PC and PG in the post-experimental period. Mechanic foot stimulation did not have a noteworthy effect on the hemostasis system functioning during immersion, whereas electromyostimulation increased procoagulant and fibrinolytic activity in blood plasma.

Within the period of 2000 to 2012 the values of 40 diagnostically significant biochemical indices in venous blood were being determined during the pre-flight clinical and physiological examination of 28 Russian cosmonauts aged 35 to 54, members of main and back-up crews of expeditions to the International Space Station. The above examination was conducted 45-30 days prior to the launch. Taking account of the fact that each of the most of the cosmonauts performed several flights over the mentioned period and they were repeatedly included in back-up crews over and over again, each of cosmonauts participated in pre-flight examinations 1 to 5 times. Reference values were calculated for each of the studied indices. It was found that reference interval boundaries for 15 indices were narrower as compared to the generally accepted ranges. The upper boundaries of activity reference ranges of a number of enzymes, as well as of concentration of some metabolites of energy and plasticity metabolism were raised relative to mean population values. Thus, it was found that Russian cosmonauts being a specific professional team featured inherent reference values which differed from mean population values in a number of blood biochemical indices. It is conditioned by peculiarities of selection, physical training and psychic and emotional status of crew members during a pre-flight period.

Microgravity is known to have a substantial effect on fluid homeostasis. The research described here was planned as part of the first joint Russian-U.S. science program carried out during a Shuttle flight. The aim of the program was to study the nature of the changes in fluid homeostasis induced by microgravity, as well as to determine the possible mechanisms underlying the regulation of fluid balance under conditions of spaceflight. To determine the effects of spaceflight on the homeostasis of fluid and electrolytes, measurements were taken of total body water, extracellular fluid plasma volumes, levels of regulatory hormones, and nutrient consumption before, during, and after a nine-day flight. Changes in renal function were studied before and after the flight. In these 2 subjects, weightlessness was not associated with a decreased extracellular fluid volume. However, there were the characteristic decreases in plasma atrial natriuretic peptide concentrations, and increases in plasma and urinary cortisol. Results indicated decreased urine volume, even through the first 48 hours of flight. Fluid volumes and glomerular filtration rate were increased after landing, probably related to the saline-loading countermeasure used by Shuttle crewmembers. The information obtained as a result of this research will facilitate the development of future research programs, as well as preventive measures for future long-duration spaceflights.