title: Prevention of hyperoxia-induced bronchial hyperreactivity by sildenafil and vasoactive intestinal peptide: impact of preserved lung function and structure.
abstract: OBJECTIVE
  Hyperoxia exposure leads to the development of lung injury and bronchial hyperreactivity (BHR) via involvement of nitric oxide (NO) pathway. We aimed at characterizing whether the stimulation of the NO pathway by sildenafil or vasoactive intestinal peptide (VIP) is able to prevent the hyperoxia-induced development of BHR. The respective roles of the preserved lung volume and alveolar architecture, the anti-inflammatory and anti-apoptotic potentials of these treatments in the diminished lung responsiveness were also characterized.
  
  
  METHODS
  Immature (28-day-old) rats were exposed for 72 hours to room air (Group C), hyperoxia (>95%, Group HC), or hyperoxia with the concomitant administration of vasoactive intestinal peptide (VIP, Group HV) or sildenafil (Group HS). Following exposure, the end-expiratory lung volume (EELV) was assessed plethysmographically. Airway and respiratory tissue mechanics were measured under baseline conditions and following incremental doses of methacholine to assess BHR. Inflammation was assessed by analyzing the bronchoalveolar lavage fluid (BALF), while biochemical and histological analyses were used to characterize the apoptotic and structural changes in the lungs.
  
  
  RESULTS
  The BHR, the increased EELV, the aberrant alveolarization, and the infiltration of inflammatory cells into the BALF that developed in Group HC were all suppressed significantly by VIP or sildenafil treatment. The number of apoptotic cells increased significantly in Group HC, with no evidence of statistically significant effects on this adverse change in Groups HS and HV.
  
  
  CONCLUSIONS
  These findings suggest that stimulating the NO pathway by sildenafil and VIP exert their beneficial effect against hyperoxia-induced BHR via preserving normal EELV, inhibiting airway inflammation and preserving the physiological lung structure, whereas the antiapoptotic potential of these treatments were not apparent in this process.
authors.forename: Dorottya
authors.initials: D
authors.lastname: Czövek
authors.forename: Ferenc
authors.initials: F
authors.lastname: Peták
authors.forename: Yves
authors.initials: Y
authors.lastname: Donati
authors.forename: Xavier
authors.initials: X
authors.lastname: Belin
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Pache
authors.forename: Constance
authors.initials: C
authors.lastname: Barazzone Argiroffo
authors.affiliation: Department of Anesthesiology, Anesthesiological Investigation Unit, Pharmacology and Intensive Care, University of Geneva, Geneva, Switzerland. walid.habre@hcuge.ch.
authors.forename: Walid
authors.initials: W
authors.lastname: Habre
mesh_terms: D000818:Animals; D016535:Bronchial Hyperreactivity / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D018496:Hyperoxia / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D008168:Lung / Q000187:drug effects / Q000502:physiology*; D008297:Male; D010879:Piperazines / Q000494:pharmacology / Q000627:therapeutic use*; D011687:Purines / Q000494:pharmacology / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D000068677:Sildenafil Citrate; D013449:Sulfonamides / Q000494:pharmacology / Q000627:therapeutic use*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D010879:Piperazines; D011687:Purines; D013449:Sulfonamides; D014660:Vasoactive Intestinal Peptide; D000068677:Sildenafil Citrate