title: Circulating levels of cell-derived microparticles are reduced by mild hypobaric hypoxia: data from a randomised controlled trial.
abstract: OBJECTIVE
  Hypoxia is known to induce the release of microparticles in vitro. However, few publications have addressed the role of hypoxia in vivo on circulating levels of microparticles. This randomised, controlled, crossover trial aimed to determine the effect of mild hypoxia on in vivo levels of circulating microparticles in healthy individuals.
  
  
  METHODS
  Blood was obtained from 51 healthy male volunteers (mean age of 26.9 years) at baseline altitude (490 m) and after 24 and 48 h at moderate altitude (2,590 m). The order of altitude exposure was randomised. Flow cytometry was used to assess platelet-poor plasma for levels of circulating microparticles derived from platelets, endothelial cells, leucocytes, granulocytes, monocytes, red blood cells and procoagulant microparticles.
  
  
  RESULTS
  Mean (standard deviation) oxygen saturation was significantly lower on the first and second day after arrival at 2,590 m, 91.0 (2.0) and 92.0 (2.0) %, respectively, compared to 490 m, 96 (1.0) %, p < 0.001 for both comparisons. A significant decrease in the levels of procoagulant microparticles (annexin V+ -221/μl 95 % CI -370.8/-119.0, lactadherin+ -202/μl 95 % CI -372.2/-93.1), platelet-derived microparticles (-114/μl 95 % CI -189.9/-51.0) and red blood cell-derived microparticles (-81.4 μl 95 % CI -109.9/-57.7) after 48 h at moderate altitude was found. Microparticles derived from endothelial cells, granulocytes, monocytes and leucocytes were not significantly altered by exposure to moderate altitude.
  
  
  CONCLUSIONS
  In healthy male individuals, mild hypobaric hypoxia, induced by a short-term stay at moderate altitude, is associated with lower levels of procoagulant microparticles, platelet-derived microparticles and red blood cell-derived microparticles, suggesting a reduction in thrombotic potential.
authors: Department of Clinical Immunology, Churchill Hospital, Oxford University Hospitals NHS Trust, Oxford, OX3 7LJ, UK, lisa.ayers@nhs.net.
authors: Lisa
authors: L
authors: Ayers
authors: Anne-Christin
authors: AC
authors: Stoewhas
authors: Berne
authors: B
authors: Ferry
authors: Tsogyal D
authors: TD
authors: Latshang
authors: Christian M
authors: CM
authors: Lo Cascio
authors: Ross
authors: R
authors: Sadler
authors: Katrin
authors: K
authors: Stadelmann
authors: Noemi
authors: N
authors: Tesler
authors: Reto
authors: R
authors: Huber
authors: Peter
authors: P
authors: Achermann
authors: Konrad E
authors: KE
authors: Bloch
authors: Malcolm
authors: M
authors: Kohler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000531:Altitude; D016022:Case-Control Studies; D055252:Cell-Derived Microparticles / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011897:Random Allocation