[Characteristics of the regional circulation and vasomotor regulation after a 2-month space flight]

The paper presents the results of rheographic study of regional hemodynamics of Soyuz-18 -- Salyut-4 crewmembers at rest and during orthostatic tests before and after their 63-day space flight. On the 1st postflight day a marked decrease of dicrotic and diastolic indices in hemispheric rheoencephalograms of both cosmonauts and in bimastoidal rheoencephalograms of V.I. Sevastyanov was noted. These events of cerebral and venous hypotension were followed in V.I. Sevastyanov by a noticeable increase in the cerebral pulse blood filling and in P.I. Klimuk by a slight decrease of the hemispheric blood filling. A marked asymmetry of rheoencephalograms, especially of the vascular tone, was detected. On the 1st postflight day orthostatic tolerance was diminished, particularly in P.I. Klimuk. He showed predominant phenomena of arteriolar and venous hypotension of cerebral vessels in the vertebral-basillary system and V.I. Sevastyanov exhibited hypotension primarily in the basin of the interior carotid artery. Responses of the regional hemodynamics to orthostatic tests in both cosmonauts improved continuously and reached the preflight level by the 16th postflight day.