Plasma and blood volume in space.

Diedrich A, Paranjape SY, Robertson D
Am J Med Sci. 2007 334 (1): 80-5

PMID: 17630598 · DOI:10.1097/MAJ.0b013e318065b89b

Body fluid regulation is affected by gravity. The primary mechanisms of the etiology of hypovolemia found in simulation studies on earth and after space flight are different. The increased diuresis after increase of central blood volume postulated by Henry Gauer could not be found. Based on recent findings, new hypotheses about fluid volume regulation during space flight have emerged. The reduced blood volume in space is the result of 1) a negative balance of decreased fluid intake and smaller reduction of urine output; 2) fast fluid shifts from the intravascular to interstitial space as the result of lower transmural pressure after reduced compression of all tissue by gravitational forces especially of the thorax cage; and 3) fluid shifts from intravascular to muscle interstitial space because of less muscle tone required to maintain body posture. Additionally, loss of erythrocytes reduces blood volume. The attenuated diuresis during space flight can be explained by increased retention after stress-mediated sympathetic activation during initial phase of space flight, stimulation caused by reduced red cell mass, and activation after fast blood volume contraction. Additionally, the relation between plasma osmolarity and vasopressin release might be disturbed in microgravity.

MeSH Terms (9)

Blood Volume Fluid Shifts Gravitation Humans Hypovolemia Plasma Volume Space Flight Weightlessness Weightlessness Countermeasures

Connections (1)

This publication is referenced by other Labnodes entities: