[Dynamics of the redistribution of human blood in response to lower body negative pressure].

During exposure to LBNP of -10 to -60 mm Hg variations in the blood filling of body segments were measured, using 59Fe labelled erythrocytes. The study was performed on 10 healthy volunteers each of which was exposed to six LBNP sessions (in recumbency). The data obtained were related to changes in the blood filling of various body segments (head, thorax, abdomen, pelvis, legs) which were most pronounced at LBNP -20 to -30 mm Hg.

[Characteristics of the reaction of the cardiovascular system during the immediate aftereffects of LBNP].

Circulation variations during LBNP immediate aftereffects were investigated. The test subjects with different test tolerance showed dissimilar cardiovascular responses. The lack of reflex bradycardia in the test subjects with reduced LBNP tolerance gives evidence that their regulatory mechanisms are insufficiently reactive; this is manifested during aftereffects of low LBNP (up to -40 mm Hg).

[Theoretical values for left ventricular ejection time during weightlessness].

The relationship between duration of blood ejection and cardiac cycle at rest can be well described by a linear function. This relationship is maintained in weightlessness as well. The derived formula used in calculations of the theoretical values of the ejection phase during an exposure to LBNP makes it possible to predict LBNP test tolerance in the weightless state.

[Blood circulation under physical load in the crew members of the 1st Saliut-6 base expedition].

During the 96-day flight aboard the Salyut-6 station the crewmembers showed a satisfactory response to bicycle ergometry of moderate load. However, cardiovascular regulation during exercise declined, particularly by the end of the first and the beginning of the second month. This was mainly associated with deconditioning due to an inadequate work load.