Subject(s)
Blood Volume/physiology , Body Water/physiology , Posture/physiology , Adult , Humans , Male , Middle AgedABSTRACT
Hemodynamic effects of simulated microgravity were investigated, in various experiments, using radioactive isotopes, in which 40 healthy men, aged 35 to 42 years, took part. Blood shifts were evaluated qualitatively and quantitatively. Simulation studies included bedrest, head-down tilt (-5 degrees and -15 degrees), and vertical water immersion, it was found that none of the methods could entirely simulate hemodynamic effects of microgravity. Subjective sensations varied in a wide range. They cannot be used to identify reliably the effects of real and simulated microgravity. Renal fluid excretion in real and simulated microgravity was different in terms of volume and time. The experiments yielded data about the general pattern of circulation with blood displaced to the upper body.
Subject(s)
Bed Rest/adverse effects , Fluid Shifts/physiology , Head-Down Tilt/adverse effects , Hemodynamics/physiology , Immersion/adverse effects , Weightlessness Simulation/methods , Adult , Evaluation Studies as Topic , Humans , Male , Plasma Volume/physiology , Supine Position , Time Factors , Weightlessness Simulation/adverse effectsABSTRACT
Body fluid variations were examined during 120-day antiorthostatic (-5 degrees) hypokinesia in 21 test subjects, 9 of which comprised a control group (Group 1). The remaining 12 subjects formed three groups (four subjects each) who received drugs to normalize mineral and lipid metabolism (Group 2), or performed specially developed exercises (Group 3), or were on the combined treatment (Group 4). Total body water (TBW), intracellular fluid volume (IFV), extracellular fluid volume (EFV), and EFV composition were measured by nuclear physical methods. Measurements were taken prior to exposure, on head-down tilt days 1, 60 and 120, and on recovery day 15. Body composition and K40 content were investigated before and after head-down tilt. The controls showed body dehydration that began on tilt day 1 at the expense of vascular fluid and continued by day 60 at the expense of interstitial fluid and by day 120 at the expense of IFV. Group 2 subjects exhibited variations that were similar to those of controls. Group 3 subjects were in better shape due to the beneficial effect of exercise which diminished as head-down tilt continued. In the recovery period the above changes regressed.
Subject(s)
Blood Volume/physiology , Body Fluids/physiology , Immobilization/physiology , Models, Biological , Posture/physiology , Body Water/physiology , Extracellular Space/physiology , Humans , Intracellular Fluid/physiology , Time FactorsABSTRACT
Using radioactive isotopes, central, peripheral and organ blood circulation was investigated in two rhesus-monkeys before the 7-day space flight, 1.5 hours after touchdown, and 4 months after recovery. Blood distribution and shifts were measured in different body segments, viz. head, chest, abdomen, legs. Postflight measurements revealed a decrease of plasma and blood volume. They also demonstrated changes in cardiac output and stroke volume, decrease of total peripheral resistance, reduction of mean arterial pressure and a slight increase of heart rate. Pulmonary blood flow velocity and time varied insignificantly and in a different manner. Blood was pooled in the legs. Blood flow velocity in the skin of the upper and lower body decreased while in muscles it increased above the baseline values. Postflight, muscles acted as a hemodynamic blood pool. The tolerance of both monkeys to the tilt test was satisfactory. It can be concluded that the monkeys tolerated the 7-day space flight well enough.
Subject(s)
Blood Circulation , Haplorhini/physiology , Space Flight , Animals , Blood Volume , Hemodynamics , Radioisotope Dilution Technique , Time Factors , USSRABSTRACT
Using nuclear physics methods, hydration homeostasis of three monkeys flown on Cosmos-1514 and Cosmos-1667 was investigated. Measurements were made before flight 1.5 hours after touchdown and during the recovery period. Total water content, extracellular and tissue fluid volumes were measured and intracellular and interstitial fluid volumes were calculated. Postflight, all the animals showed hydration status changes of similar sign: total water content, intracellular and extracellular fluid volumes decreased. Most significant changes occurred in tissue and interstitial fluid volumes. Hydration status responses to space flight factors were variable and the above changes disappeared in the course of the recovery period. The variations recorded were viewed as adaptive.
Subject(s)
Body Water/physiology , Haplorhini/physiology , Homeostasis , Space Flight , Animals , Body Water/analysis , Body Weight , Extracellular Space/analysis , Extracellular Space/physiology , Intracellular Fluid/analysis , Intracellular Fluid/physiology , Time Factors , USSRABSTRACT
The hydratation status of 15 patients of various age groups with hypothyrosis was studied using nuclear physical methods. Their body composition was calculated. All the examinees demonstrated considerable hyperhydratation of the extracellular water sector with prevailing liquid accumulation in the interstitial space. Some changes in the infrastructure of the hydratation status including those in the nature of interrelationships of liquid media, were noted. The dependence of the hydratation status and its infrastructure in patients with hypothyrosis on age and gravity of disease but not on its duration was revealed.
Subject(s)
Body Water/metabolism , Hypothyroidism/metabolism , Adolescent , Adult , Age Factors , Female , Humans , Male , Middle AgedABSTRACT
Sodium balance and circulating plasma, intracellular, extracellular and interstitial fluid volumes were measured in the test subjects exposed for 120 days to head-down tilt at -5 degrees. The large scatter of the above parameters was associated with individual variations and with the use of different countermeasures against demineralization (exercise and drugs-xydiphone and glucamak). The effect of the countermeasures was different both in qualitative and quantitative terms. It appears that the target of their action was different. The best prophylactic effect was seen when exercise and drugs were used in combination. These findings suggest that individual variations of fluid-electrolyte metabolism during prolonged hypokinesia are related to the different capacity of tissues for water and electrolytes.
Subject(s)
Bed Rest , Posture , Water-Electrolyte Balance , Water-Electrolyte Imbalance/prevention & control , Adult , Bed Rest/adverse effects , Body Water/drug effects , Body Water/metabolism , Etidronic Acid/therapeutic use , Humans , Male , Physical Exertion , Plasma Volume/drug effects , Sodium/metabolism , Time Factors , Water-Electrolyte Balance/drug effectsABSTRACT
The physiological effects of zero-g were simulated by 6-hour antiorthostatic hypokinesia at -15 degrees, using eight healthy volunteers. They took part in two experimental runs at a 2 week interval. During the first study the test subjects received a placebo and during the second study they got 6 mg dihydroergotamine methane sulfonate per os. Radiometric examinations of the whole body and its compartments (head, chest, abdomen, legs) showed that the drug increased blood pooling in the upper body and decreased it in the lower body at every position of the long axis of the body relative to the gravity vector.
Subject(s)
Blood Circulation/drug effects , Dihydroergotamine/pharmacology , Posture , Adult , Blood Pressure/drug effects , Blood Volume/drug effects , Heart Rate/drug effects , Humans , Male , Plasma Volume/drug effectsABSTRACT
Man's orthostatic tolerance and physical work capacity declined in response to 6-hour head-down tilt at -15 degrees. During tilt tests heart rate increased, blood pressure fell, and blood pooling in the upper body decreased. During exercise tests the circulating blood volume, total amount of the work performed, and consumed oxygen decreased. Sydnocarb given at a dose of 25 mg during head-down tilt did not influence the circulating blood volume and oxygen consumption. All other parameters varied approaching the pretest values.
Subject(s)
Blood Circulation/drug effects , Hemodynamics/drug effects , Immobilization , Oxadiazoles/pharmacology , Posture , Sydnones/pharmacology , Adult , Blood Pressure/drug effects , Blood Volume/drug effects , Electrocardiography , Exercise Test , Heart Rate/drug effects , Humans , Male , Oxygen Consumption/drug effects , Time FactorsABSTRACT
A prolonged head-down tilt resulted by the end of the second month in a significant decrease in the circulating blood volume at the expense of plasma and erythrocyte volumes. One of the factors that caused a reduction in the erythrocyte volume was their survival time shortening. The fact that during the rest four hypokinetic months there was no further decline in the erythrocyte count was attributed to adaptive developments: increase of bone marrow production and rate of differentiation of erythroid elements. Exercises used as a countermeasure could slightly counteract the adverse effects of head-down tilt.
