Fluid and Electrolyte Metabolism and Hormonal Regulaltion of Fluid Volume (Diurez (Diuresis)) - 07.15.15

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Science Objectives for Everyone
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Science Results for Everyone
Electrolytes (ie. sodium and potassium)affect the amount of water in our body fluids as well as muscle function and other important processes. This experiment evaluated how metabolism of electrolytes changes in microgravity. Data showed that younger crew members tend to have a lower body mass index and more muscular crew members show an increased blood concentration of potassium. Data also showed changes in hormones involved in signaling in the central nervous system. Such changes could affect blood pressure, cardiac output, and balance in long-term flight. These factors will be useful in evaluating nutritional status and physical and mental activities of crewmembers during and after flight. 

The following content was provided by Irina M. Larina, and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Irina M. Larina, Institute for Biomedical Problems, Moscow, Russia

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Sponsoring Space Agency
Russian Federal Space Agency (Roscosmos)

Sponsoring Organization
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Research Benefits
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ISS Expedition Duration
August 2001 - April 2005

Expeditions Assigned

Previous ISS Missions
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Experiment Description

Research Overview
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Reception of new data on the water-salt metabolism status and hormonal control of volimia in zero-gravity conditions and during post-flight readaptation period.

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Space Applications
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Earth Applications
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Operational Requirements
Plasma-03 centrifuge to separate blood into plasma and serum, Plasma-03 set of accessories for sampling, Gematokrit Kit to take blood samples and separate plasma from erythrocytes defining hematocrit number, Reflotron-4 Kit capillary blood count for hemoglobin, creatinine and urea, KV-03 Container, Plasma-03 Kit for taking, processing and storage of venous blood and urine, M-Priemniki Kit to study water-salt metabolism, Cryogem-03 refrigerator to freeze blood samples.

Operational Protocols
Study of the dependence between renal elimination activity and its hormonal control. Study of the balance of liquid and main electrolytes.

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Results/More Information

It is well documented that space flight conditions cause loss of minerals, strength, and structural changes in bone tissue resulting in negative calcium balance in bone and the entire body. Biochemical markers in the blood such as osteocalcin (OC), a noncollagenic protein synthesized mostly by osteoblasts (bone building cells) for the formation of new bone, and collagen fragments, from bone disintegration, were measured to evaluate bone tissue metabolism of nine Russian cosmonauts who performed space flights for 129–196 days on the ISS during the period from 2000 to 2003. In addition, the activity of the system regulating the body’s calcium turnover was assessed by the levels of parathyroid hormone (PTH) and calcitonin (CT), both function to regulate calcium in the blood, as well as total calcium and calcium ions concentrations. Blood samples for the study were obtained during routine medical examination at 30–45 days before the mission, the day of landing, days 7–8, and 15–19 days after landing. Analysis showed the concentration of OC and collagen fragments were 25% and 50% higher, respectively, after landing than before launch indicating persistent high activity of bone loss due to the activation of two processes: bone tissue resorption (an increase in collagen fragments), and new bone formation (an increase in OC) despite ending exposure to microgravity. The destruction of bone collagen slowly but steadily decreased after prolonged space flight, whereas remodeling (process of building new bone tissue) had a latency period and lasted for a long time. Both CT and PTH levels remain elevated at 17 days after flight, and hormonal changes revealed that calcium metabolism was affected not only by PTH and CT but also by increase in the stress hormone cortisol. Total calcium concentration did not change, however, its ionized fraction tended to increase during flight and early postflight period. Data indicate that the recovery of the normal balance between resorption and new bone tissue formation has different rates. In some cases, a strong correlation between the levels of collagen fragments and calcium ions in the blood was observed, meaning that destruction of the collagen matrix of the bone in these subjects makes the greatest contribution to bone mineral imbalance. These results have theoretical and practical implications: a decrease in the mineral saturation of bone tissue and remodeling of its structure under the influence of space flight are adaptive during exposure to microgravity and appear reversible with the initial state observed before the flight eventually being attained. Further tests are necessary to find out the duration of this process and the rate-limiting components.

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Results Publications

    Morukov BV, Nichiporuk IA, Tret'yakov VS, Larina IM.  Biochemical Markers of Bone Tissue Metabolism in Cosmonauts After a Prolonged Spaceflight. Human Physiology. 2005; 31(6): 684-687. DOI: 10.1007/s10747-005-0115-z.

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Ground Based Results Publications

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ISS Patents

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Related Publications

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Related Websites
Energia - Science Research on the ISS Russian Segment

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