title: Plasma volume and flight duration effects on post-spaceflight soluble adhesion molecules.
abstract: BACKGROUND
  We examined the effects of plasma volume (PV) changes and flight duration on circulating soluble adhesion markers (sP-selection, sE-selection, and sICAM-1).
  
  
  METHODS
  Study participants were 22 astronauts (2 women). Missions ranged from 5 to 16 d. Astronauts were split into two groups: those who spent less than 8 d in space and those who spent more than 8 d in space. Soluble adhesion markers and PV were assessed 10 d prelaunch, immediately after landing, and 2-4 d postflight.
  
  
  RESULTS
  Compared to prelaunch, PV significantly decreased by 4.9% after landing and increased by 9.9% 2-4 d postflight. After landing, sICAM-1 decreased (233.15 vs. 226.78 ng · ml⁻¹) and remained lowered 2-4 d after landing (223.25 ng · ml⁻¹). Adjusting for PV changes, sICAM-1 upon landing was less than prelaunch (218.23 ng · ml⁻¹), but became greater 2-4 d postflight (250.30 ng · ml⁻¹). From prelaunch to landing, sE-selection decreased significantly (30.25 vs. 28.51 ng · ml⁻¹) and returned to prelaunch levels 2-4 d postflight (30.10 ng · ml⁻¹). Adjusting for PV changes, sE-selection was significantly greater 2-4 d postflight (33.48 ng · ml⁻¹) compared to prelaunch. In those who spent less than 8 d in space only, sP-selection increased from prelaunch levels to landing day (31.66 vs. 48.06 ng · ml⁻¹), with and without adjustment for PV changes. Flight duration did not influence PV, sICAM-1, or sE-selection.
  
  
  CONCLUSIONS
  Spaceflight leads to an internal environment that decreases PV during flight but rebounds after flight, leading to a dilution of sICAM-1 and sE-selection, but does not appear to affect sP-selection. Flight duration only affected sP-selection.
authors.affiliation: University of California - San Diego, San Diego, CA, USA.
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Austin
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Patterson
authors.forename: Michael G
authors.initials: MG
authors.lastname: Ziegler
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Mills
mesh_terms: D000328:Adult; D018480:Astronauts; D015415:Biomarkers / Q000097:blood; D015815:Cell Adhesion Molecules / Q000097:blood*; D019040:E-Selectin / Q000097:blood; D005260:Female; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000097:blood; D008297:Male; D019007:P-Selectin / Q000097:blood; D010953:Plasma Volume; D013026:Space Flight; D013997:Time Factors
chemical_list: D015415:Biomarkers; D015815:Cell Adhesion Molecules; D019040:E-Selectin; D019007:P-Selectin; D018799:Intercellular Adhesion Molecule-1