[Central and regional hemodynamics during LBNP exposure studied by isotopic and impedance methods].

The potential of impedance and isotope (intravenous injections of 131I and 113mIn) methods to study regional and central hemodynamics was investigated on 12 test subjects exposed to LBNP. Both methods demonstrated marked changes in blood filling of the head and the chest, particularly during the first minutes of LBNP tests. This occurred together with a drastic increase in leg blood filling.

[Feasibility of using a test involving exposure of the lower half of the body to negative pressure for selection of cosmonaut candidates].

By means of regional rheography and electrocardiography cardiovascular reactions to LBNP (25 mm Hg--2 min; 35 mm Hg--3 min; 40 mm Hg--5 min; 50 mm Hg--5 min) were studied in 60 young male test subjects (aged 25--42). Changes in the content and excretion of catecholamines were followed before and after LBNP in II test subjects. The investigations helped to elucidate mechanisms of compensatory and related reactions of the cardiovascular and sympathoadrenal systems.