title: Sildenafil and bosentan improve arterial oxygenation during acute hypoxic exercise: a controlled laboratory trial.
abstract: OBJECTIVE
  Sildenafil and, recently, bosentan have been reported to increase arterial saturation and exercise capacity at altitude. The mechanisms behind this are still poorly defined but may be related to attenuation of hypoxic pulmonary vasoconstriction (HPV) and improved gas exchange. This study was designed to examine and compare the effect of sildenafil and bosentan on pulmonary gas exchange during acute hypoxic exercise in a controlled laboratory setting.
  
  
  METHODS
  Sixteen athletic university students (8 males, 8 females) were examined during exercise in a hypoxic chamber (11% oxygen) before and after the administration of either sildenafil (n=10) or bosentan (n=6). Respiratory and metabolic measurements were taken at rest and during increasing exercise intensity (up to 90% of their individual maximal oxygen uptake [VO(2)max]) in concert with arterial blood gas sampling.
  
  
  RESULTS
  Both drugs resulted in small, but significant increases in arterial PO(2) (2-3 Torr) and O(2) saturation (3-4%) at rest and during hypoxic exercise, in both men and women. No significant changes in arterial PCO(2) or ventilation were seen at rest or during exercise in hypoxia; however, heart rate (both at rest and during exercise) was increased with both sildenafil and bosentan in both men and women.
  
  
  CONCLUSIONS
  These data demonstrate that sildenafil and bosentan equally improve arterial oxygenation in acute hypoxia in both men and women, which could account for improved physical performance at altitude.
authors: Center for Cardiovascular and Respiratory Sciences, Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV 26506, USA. molfert@hsc.wvu.edu
authors: I Mark
authors: IM
authors: Olfert
authors: Alexander
authors: A
authors: Loeckinger
authors: Benedikt
authors: B
authors: Treml
authors: Martin
authors: M
authors: Faulhaber
authors: Markus
authors: M
authors: Flatz
authors: Martin
authors: M
authors: Burtscher
authors: Susanne
authors: S
authors: Truebsbach
authors: Axel
authors: A
authors: Kleinsasser
mesh_terms: D000328:Adult; D000531:Altitude; D000077300:Bosentan; D002302:Cardiac Output; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D009051:Mountaineering; D010100:Oxygen / Q000097:blood; D010879:Piperazines / Q000008:administration & dosage / Q000627:therapeutic use*; D011659:Pulmonary Gas Exchange; D011687:Purines / Q000008:administration & dosage / Q000627:therapeutic use; D000068677:Sildenafil Citrate; D013449:Sulfonamides / Q000008:administration & dosage / Q000627:therapeutic use*; D013450:Sulfones / Q000008:administration & dosage / Q000627:therapeutic use*; D016896:Treatment Outcome; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D010879:Piperazines; D011687:Purines; D013449:Sulfonamides; D013450:Sulfones; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate; D000077300:Bosentan; D010100:Oxygen