title: The relation between intraocular pressure change and plasma natriuretic peptide under simulated hypobaric conditions.
abstract: OBJECTIVE
  To ascertain whether the changes in intraocular pressure (IOP) that occur during hypobaric hypoxic exposure are related to plasma N-terminal pro-brain natriuretic peptide (BNP) levels.
  
  
  METHODS
  The study group comprised 26 healthy participants (all male, mean age 23.1 years). IOP was measured at local ground level, (792 m above sea level), then while in a chamber providing hypobaric hypoxic conditions (the subjects were exposed to a pressure equivalent to 9144 m for 1-3 min), and again after exit from the chamber. In each condition, the mean of three consecutive measurements of IOP was calculated for each eye. For BNP measurements, blood samples were drawn before the participants entered the chamber and just after they left the chamber.
  
  
  RESULTS
  IOP during hypobaric hypoxic exposure (18.00 +/- 3.70 mmHg) was significantly greater than that before (15.66 +/- 2.10 mmHg, P < 0.001) or after (16.10 +/- 2.63 mmHg, P = 0.001) the exposure. IOP levels before and after the exposure were not significantly different (P = 0.136). Plasma BNP levels measured before and after exposure to hypobaric hypoxic conditions were not significantly different (P = 0.462).
  
  
  CONCLUSIONS
  Plasma BNP levels did not change after short-term hypobaric hypoxic exposure, while the IOP increased. This increase may have been caused by some other systemic factors. As the hypobaric hypoxic conditions were reversed, IOP decreased to normal levels.
authors.affiliation: Department of Ophthalmology, Eskisehir Military Hospital, Eskisehir, Turkey.
authors.forename: Remzi
authors.initials: R
authors.lastname: Karadag
authors.forename: Ahmet
authors.initials: A
authors.lastname: Sen
authors.forename: Nilgun
authors.initials: N
authors.lastname: Yildirim
authors.forename: Hikmet
authors.initials: H
authors.lastname: Basmak
authors.forename: Haydar
authors.initials: H
authors.lastname: Golemez
authors.forename: Erdinc
authors.initials: E
authors.lastname: Cakir
authors.forename: Ahmet
authors.initials: A
authors.lastname: Akin
mesh_terms: D000328:Adult; D000531:Altitude; D001274:Atmospheric Pressure; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D007429:Intraocular Pressure; D008297:Male; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D055815:Young Adult
chemical_list: D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain