[Characteristics of the functional state of the nervous system of middle-aged persons during anti-orthostatic hypokinesia]. / Osobennosti funktsional'nogo sostoianiia nervnoi sistemy lits starshego vozrasta v usloviialkh antiortostaticheskoi gipokinezii.

The functional state of the nervous system and its autonomic compartment was investigated in 15 men, aged 40-52 years, during their 30-day exposure to head-down tilt (-8 degrees). Group 1 consisted of 9 subjects with early manifestations of cerebral atherosclerosis and Group 2 included 6 subjects with cerebral atherosclerosis and arterial hypertension. The control group incorporated 9 healthy volunteers, aged 25-39 years. During adaptation to head-down tilt, middle-aged and young subjects showed consistent changes in the nervous system. In response to perturbation effects, autonomic reactions were inert and autonomic support was excessive. However delayed onset of responses, duration and slow recovery of the parameters examined indicated that mechanisms of autonomic regulation were inadequate. These changes were most distinct in middle-aged subjects, particularly in Group 2 subjects: recovery of the functional state of the nervous system was completed by day 20 in middle-aged subjects and by day 9 in young subjects. The observations have demonstrated that the nervous system of most middle-aged subjects (taking into consideration age-related and atherosclerotic changes) has a sufficiently high level of functional capabilities during medium-duration head-down tilt studies.

[Effect of exogenous cardiosynchronized contrapulsation on human regional and central hemodynamics]. / Vliianie naruzhnoi kardiosinkhronizirovannoi kontrpul'satsii na regionarnuiu i tsentral'nuiu gemodinamiku cheloveka.

Variations in regional and central hemodynamics of man under the influence of exogenous contrapulsation (ECP) were examined rheographically. In recumbent subjects, ECP increased cerebral pulse blood filling, particularly of the vertebrobasilar system. It appears that the significant increase of the tone of arterioles and veins may be important when it becomes necessary to correct cerebral circulation in the situations that may lead to brain ischemia. It has been found that in the orthostatic tilt test ECP can be an effective tool for enhancing brain and lung blood supply and increasing stroke volume, cardiac output and blood pressure. This may help maintain homeostasis and improve orthostatic tolerance. The observation that ECP may facilitate blood supply of the vitally important organs, specifically brain, enables us to recommend this procedure to be used at an early stage of readaptation after simulation or real space flights.

[Reaction of blood circulation to antiorthostatic hypokinesia in men aged 45-52]. / Reaktsii krovoobrashcheniia na antiortostaticheskuiu gipokinesiiu u muzhin 45-52 let.

Regional and central circulation reactions to 30-day antiorthostatic hypokinesia were investigated in 15 men, aged 45 to 52 years, with early signs of cerebrovascular and aortic atherosclerosis, neurocirculatory dystonia of the hypertensive type, and hypertensive disease of stage I. Regional and central hemodynamics of the subjects of the three groups during and immediately after exposure developed in a different manner.

[Changes in regional and central hemodynamics during a 7-day immersion in water]. / Izmeneniia regional'noi i tsentral'noi gemodinamiki pri 7-sutochnoi vodnoi immersii.

Regional and central hemodynamics were assessed at bi- and tetrapolar rheography and tacho-oscillography during 7-day "dry" immersion and 8-day -8 degrees head-down tilt. Blood redistribution evident from enhanced pulse filing of the brain, lungs and arms was most pronounced on day 3-5. The onset of the blood outflow to the liver was observed on immersion day 5 due to compensatory and adaptive reactions. Lack of exercise tolerance of cardiovascular system through its insufficient training was similar in the immersion and head-down tilt for all the 6 healthy males studied (aged 41-49) despite more obvious changes in regional hemodynamics during the immersion, which recovered on its fifth day.

[Features of the atropine test in persons of different ages]. / Osobennosti atropinovoi proby u lits raznogo vozrasta.

The diagnostic value of the atropine test was investigated in 47 essentially healthy men of different age groups (25-39, 40-49 and 50-59 years). The cardiovascular responses were evaluated from ECG recorded continuously for an hour after subcutaneous injection of 1.0-0.1% atropine sulphate. Atropine caused a two-stage effect of the cardiac chronotropic function. The first, bradycarditic, stage was induced by vagal stimulation while the second, tachycarditic, stage was, by contrast, produced by atropine blockade of the acetylcholine effect on M-cholinoreceptors of myocardial cells. The atropine effect was identical in sign in all age groups. However, in the young age group the bradycarditic effect was more distinct and atropine-induced arrhythmias were more frequent. In the 50-59 years subjects the tachycarditic effect grew at a slower rate and the electric systole response to a higher heart rate was less pronounced.

[Compensatory-adaptive reactions of regional hemodynamics to weightlessness during a long space flight]. / Kompensatorno-prisposobitel'nye reaktsii regionarnoi gemodinamiki k nevesomosti pri dlitel'nom kosmicheskom polete.

This paper discusses regional hemodynamics and vascular regulation during and after space flights of over 3 months in duration. Mechanisms of cardiovascular adaptation to weightlessness are described. The postflight differences in the recovery of regional hemodynamics seem to depend on the individual characteristics, age-related changes of the cardiovascular system, as well as the countermeasures and rehabilitation measures performed during and after flight.

[Features of the functional capabilities of the bodies of older persons exposed to simulated space flight factors]. / Osobennosti funktsional'nykh vozmozhnostei organizma lits starshego vozrasta pri vozdeistvii modelirovannykh faktorov kosmicheskogo poleta.

In response to simulated space flights cardiovascular and metabolic changes of 86 volunteers, aged 40-49 and 50-56, were similar to those of young people (25-39 years old). In most aged test subjects, the changes produced by 8-day head-down tilt (-8 degrees) and 7-day water immersion were moderate and reversible. This type of variation of the adaptive-compensatory reactions give evidence that aged people have sufficiently high functional capabilities. Nevertheless, 36% test subjects, aged 40-49, and 50% test subjects, aged 50-56, displayed certain features suggesting a reduction of the adaptive-compensatory capabilities (functional reserves) as a result of age-related and atherosclerotic changes of the cardiovascular system.

[Hemo- and neurodynamics of the human brain during exposure to moderate hypoxic hypoxia]. / Gemo- i neirodinamika golovnogo mozga cheloveka pri vozdeistvii umerennoi gipoksicheskoi gipoksii.

Synchronous electro- and rheoencephalography were used to study tolerance to moderate hypoxic hypoxia for 30 min at an altitude of 5000 m without additional oxygen supply. As test subject, men with autonomic-vascular dystonia (29-39 years old), 15 men over 40 (41-56 years old), and 16 essentially healthy controls (23-36 years old) were used. The aged volunteers (41-56 years old) did not differ from the controls with respect to their tolerance to hypoxic hypoxia. The men with early symptoms of hypertonic-type dystonia also showed high tolerance to hypoxic hypoxia. The subjects with hypotonic-type dystonia displayed lower tolerance.

[Postural hemodynamic shifts following short-term space flights]. / Postural'nye gemodinamicheskie sdvigi posle kratkovremennykh kosmicheskikh poletov.

Variations in the pulse blood content and tone of cerebral vessels, vertebrobasilar system, lungs and legs during the antiorthostatic tests were examined rheographically in 14 cosmonauts after 8-day space flights. The results of adaptation of the vascular system to zero-g which included smaller changes in hemodynamic parameters of the hemispheres and vertebrobasilar system during postflight tests were seen during the first days of the recovery period. Regional hemodynamic parameters returned to the preflight level within 3 to 14 days postflight. The vascular response to the head-down tilt at --15 and --30 degrees was the most informative. This led to the recommendations concerning modifications of antiorthostatic tests to be used in the selection of space crewmembers for short-term flights.

[Regional hemodynamic changes following space flights lasting up to 8 days]. / Izmeneniia regionarnoi gemodinamiki posle kosmicheskikh poletov dlitel'nost'iu do 8 sutok.

Before and after space missions of up to 8 days in duration 14 cosmonauts were exposed to rheographic examinations to measure the pulse blood filling, tone and elasticity of cerebral vessels (in the frontal-mastoidal and bimastoidal leads), right lung and right leg vessels during tilt tests. Postflight examinations demonstrated distinct changes in the cerebral, pulmonary and peripheral circulation, thus indicating cardiovascular deconditioning. The greatest changes were seen in the tone of arteries, arterioles, and veins of the brain hemispheres, vertebro-basilar system and the leg. The changes were reversible, requiring no special correction. The changes in different vascular compartments returned to normal in a nonuniform manner: hemodynamic parameters of the lung and leg returned to the preflight level by R+3, whereas those of the brain by R+14.

[Method of rheogram analysis based on separating out its arterial and venous components]. / Metod analiza reogrammy, osnovannyi na vydelenii ee arterial'noi i venoznoi komponent.

A method for rheogram analysis has been developed which enables one to separate the two components of a rheogram, i. e. the arterial and the venous ones. These two components reflect, respectively, the pulse fluctuations of the blood content of the arterial and the venous systems. Their separation is based on substantial differences between these fluctuations during a cardiac cycle. The method is used for synchronous recording of rheograms and their first derivatives, i. e. the differential rheograms. Data obtained with the use of the method make it possible to estimate the level of the blood content of the arterial network, the peripheral vascular resistance, and the conditions of the blood backflow from the venous network in a body region being examined.

[Age characteristics of the regional hemodynamic state of cosmonauts]. / Vozrastnye osobennosti sostoiannia regionarnoi gemodinamiki kosmonavtov.

Hemodynamics of the large hemispheres of the brain, vertebral-basilar system, lungs and legs of 60 cosmonauts, aged 30-37 and 38-47, was investigated rheographically. Measurements were made in the morning, under conditions of basal metabolism and in the daytime, before orthostatic tests. Comparison of the hemodynamic parameters recorded in the morning and at the daytime and in the two age groups showed significant differences revealing the effects of different factors, first of all psychoemotional tension, on the vasomotor regulation, and greater resistance of cerebral and pulmonary vascular systems of older cosmonauts to those effects. These investigations emphasize great importance of studies of regional hemodynamics, especially rheoencephalography, not only before provocative tests but also under conditions of basal metabolism.

[Central and regional hemodynamics during LBNP exposure studied by isotopic and impedance methods]. / Izuchenie tsentral'noi i regionarnoi gemodinamiki izotopnym i impedansnym metodami pri vozdeistvii ODNT.

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. The close similarity of regional hemodynamic changes detected by the two methods gives evidence that the simple and noninvasive impedance method can be well used for the above studies.

[Prognostic importance of the head-down tilting load]. / Izuchenie prognosticheskoi znachimosti antiortostaticheskoi nagruzki.

The prognostic significance of head-down tilt at -15 degrees and -30 degrees for 6 min at each step was assessed in 40 normal men, aged 22-39. The study of mean values of the maximal amplitude, relative duration of the anacrotic phase, dicrotic and diastolic indices of hemispheric and bimastoidal rheoencephalography as well as of health condition helped to determine cerebral circulation in test subjects with good and moderate tolerance to head-down tilt and to define the criteria of tilt tolerance. The test subjects who showed good tolerance to head-down tilt displayed a simultaneous compensatory increase of the tone of large caliber arteries and arterioles that was accompanied by a noticeable increase in cerebral pulse blood filling at -15 degrees and a moderate increased at -30 degrees as well as the feeling of a slight blood rush to the head. The test subjects who displayed moderate tolerance to head-down tilt showed only an increase in the tone of large caliber vessels; they also exhibited a marked decrease in the tone of arterioles, venules and veins (especially at -30 degrees) which was combined with a significant increase in the cerebral pulse blood filling and an appearance of marked venous waves on rheoencephalograms.

[Bioelectric activity of the human brain during 180-day antiorthostatic hypokinesia and during the rehabilitation period]. / Bioélektricheskaia aktivnost' golovnogo mozga cheloveka pri 182-sutochnoi antiortostaticheskoi gipokinezii i v periode reabilitatsii.

Cerebral bioelectric activity of 18 healthy test subjects, aged 31-40, was examined during and after their 182-day head-down tilting. The test subjects were divided into a group that performed countermeasures (exercise, muscle stimulation) against hypokinesia-induced disorders and a control group. During the study EEG changes were most pronounced in the controls: alpha-rhythm amplitude, frequency and index decreased, slow wave frequency reduced, whereas index of zonal differences and amplitude of beta- and slow waves increased. Phasic changes in the central nervous system excitability in response to a flickering light of 6-25 cps were found. Typical changes in spontaneous EEG during a 3 min pulmonary hyperventilation test were enhanced. The study gives evidence that the dynamics of spontaneous EEG as well as cerebral bioelectric activity in response to flickering light and pulmonary hyperventilation are important indicators of the cerebral function, especially of the cortical activity decrease.

[Feasibility of using a test involving exposure of the lower half of the body to negative pressure for selection of cosmonaut candidates]. / Izuchenie vozmozhnosti ispol'zovaniia proby s vozdeistviem otritsatel'nogo davleniia na nizhniuiu polovinu tela primenitel'no k otboru kandidatov v kosmonavty.

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. Diagnostic and prognostic criteria to evaluate LBNP tolerance were established. The criteria can be used to assess functional capabilities of the cardiovascular system and to predict orthostatic tolerance of cosmonaut candidates.