title: Effect of acute exposure to hypoxia on electrolytes and water metabolism regulatory hormones.
abstract: BACKGROUND
  Many studies suggest the hypothesis that the pathology of high altitude could be due to an early alteration of the hormones that regulate sodium homeostasis.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the behavior of these hormones during an acute exposure to hypobaric hypoxia.
  
  
  METHODS
  We studied 26 young healthy pilot students (23.1 +/- 2.9 yrs) in a hypobaric chamber, for 3 h (samples collected at time 0, 120, and 180 min), at 5000 m ASL.
  
  
  RESULTS
  The results show an early increase of plasma renin activity (PRA) paradoxically associated to a decrease of aldosterone plasma levels. This later returned to the baseline values at 180 min, whereas PRA remained increased throughout the exposure. Both arginine-vasopressin (ADH) and the atrial natriuretic peptide (ANP) significantly increased, while a new putative hormone, the so-called digoxin-like substance (DLS) did not show significant changes.
  
  
  CONCLUSIONS
  Our data demonstrate a specific sensitivity of the hormonal systems to hypoxia, which may be influenced by the time of the exposure. The relationship with results previously reported is also addressed.
authors.affiliation: Italian Air Force, D.A.S.R.S.-Aerospace Medicine Dept., Aeroporto Pratica di Mare, Pomezia (Rome), Italy.
authors.forename: C
authors.initials: C
authors.lastname: De Angelis
authors.forename: C
authors.initials: C
authors.lastname: Ferri
authors.forename: L
authors.initials: L
authors.lastname: Urbani
authors.forename: S
authors.initials: S
authors.lastname: Farrace
mesh_terms: D000208:Acute Disease; D000328:Adult; D000337:Aerospace Medicine; D000450:Aldosterone / Q000097:blood; D001127:Arginine Vasopressin / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000097:blood; D018660:Blood Pressure Monitoring, Ambulatory; D001834:Body Water / Q000378:metabolism*; D002298:Cardenolides; D004077:Digoxin; D004791:Enzyme Inhibitors / Q000097:blood; D006339:Heart Rate; D006728:Hormones / Q000097:blood*; D006801:Humans; D000860:Hypoxia / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D011188:Potassium / Q000097:blood / Q000652:urine; D011863:Radioimmunoassay; D012083:Renin / Q000097:blood; D012503:Saponins / Q000097:blood; D012964:Sodium / Q000097:blood / Q000652:urine; D014882:Water-Electrolyte Balance / Q000502:physiology*
chemical_list: D002298:Cardenolides; D004791:Enzyme Inhibitors; D006728:Hormones; D012503:Saponins; C034504:digoxin-like factors; D001127:Arginine Vasopressin; D000450:Aldosterone; D004077:Digoxin; D009320:Atrial Natriuretic Factor; D012964:Sodium; D012083:Renin; D011188:Potassium