title: Treatment of micro air bubbles in rat adipose tissue at 25 kPa altitude exposures with perfluorocarbon emulsions and nitric oxide.
abstract: BACKGROUND
  Perfluorocarbon emulsions (PFC) and nitric oxide (NO) releasing agents have on experimental basis demonstrated therapeutic properties in treating and preventing the formation of venous gas embolism as well as increased survival rate during decompression sickness from diving. The effect is ascribed to an increased solubility and transport capacity of respiratory gases in the PFC emulsion and possibly enhanced nitrogen washout through NO-increased blood flow rate and/or the removal of endothelial micro bubble nuclei precursors. Previous reports have shown that metabolic gases (i.e., oxygen in particular) and water vapor contribute to bubble growth and stabilization during altitude exposures. Accordingly, we hypothesize that the administration of PFC and NO donors upon hypobaric pressure exposures either (1) enhance the bubble disappearance rate through faster desaturation of nitrogen, or in contrast (2) promote bubble growth and stabilization through an increased oxygen supply.
  
  
  METHODS
  In anesthetized rats, micro air bubbles (containing 79% nitrogen) of 4-500 nl were injected into exposed abdominal adipose tissue. Rats were decompressed in 36 min to 25 kPa (~10,376 m above sea level) and bubbles studied for 210 min during continued oxygen breathing (FIO2 = 1). Rats were administered PFC, NO, or combined PFC and NO.
  
  
  RESULTS
  In all groups, most bubbles grew transiently, followed by a stabilization phase. There were no differences in the overall bubble growth or decay between groups or when compared with previous data during oxygen breathing alone at 25 kPa.
  
  
  CONCLUSIONS
  During extreme altitude exposures, the contribution of metabolic gases to bubble growth compromises the therapeutic effects of PFC and NO, but PFC and NO do not induce additional bubble growth.
authors.affiliation: Laboratory of Hyperbaric Medicine, Department of Anaesthesia, Centre of Head and Orthopaedics, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark, thomas1623@gmail.com.
authors.forename: Thomas
authors.initials: T
authors.lastname: Randsøe
authors.forename: O
authors.initials: O
authors.lastname: Hyldegaard
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects*; D000531:Altitude; D000818:Animals; D003665:Decompression Sickness / Q000097:blood / Q000188:drug therapy / Q000517:prevention & control*; D004655:Emulsions / Q000627:therapeutic use; D005466:Fluorocarbons / Q000627:therapeutic use*; D009569:Nitric Oxide / Q000627:therapeutic use*; D009584:Nitrogen / Q000097:blood*; D010100:Oxygen / Q000097:blood*; D051381:Rats
chemical_list: D004655:Emulsions; D005466:Fluorocarbons; D009569:Nitric Oxide; D009584:Nitrogen; D010100:Oxygen