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Abstract
This paper presents the results of measuring central and regional (head, forearm,
calf) hemodynamics at rest and during provocative tests by the method of tetrapolar
rheography in the course of Salyut-6-Soyuz and Salyut-7-Soyuz missions. The measurements
were carried out during short-term (19 man-flights of 7 days in duration) and long-term
(21 man-flights of 65-237 days in duration) manned missions. At rest, stroke volume
(SV) and cardiac output (CO) as well as heart rate (HR) decreased insignificantly
(in short-term flights) or remained essentially unchanged (in long-term flights).
In prolonged flights CO increased significantly in response to exercise tests due
to an increase in HR and the lack of changes in SV. After exercise tests SV and CO
decreased as compared to the preflight level. During lower body negative pressure
(LBNP) tests HR and CO were slightly higher than preflight. Changes in regional hemodynamics
included a distinct decrease of pulse blood filling (PBF) of the calf, a reduction
of the tone of large vessels of the calf and small vessels of the forearm. Head examination
(in the region of the internal carotid artery) showed a decrease of PBF of the left
hemisphere (during flight months 2-8) and a distinct decline of the tone of small
vessels, mainly, in the right hemisphere. During LBNP tests the tone of pre- and postcapillary
vessels of the brain returned to normal while PBF of the right and left hemisphere
vessels declined. It has been shown that regional circulation variations depend on
the area examined and are induced by a rearrangement of total hemodynamics of the
human body in microgravity. This paper reviews the data concerning changes in central
and regional circulation of men in space flights of different duration.