title: [The changes of function and morphology of pulmonary arterial vessels in the pika at high altitude].
abstract: OBJECTIVE
  To investigate the possible mechanisms of adaptation to chronic hypoxia in the pulmonary circulation.
  
  
  METHODS
  We made direct measurements of pulmonary arterial pressure (Ppa) in 10 awake pika rodents that were transported to 2 260 m after being captured at 4 300 m and in 10 Wistar rats in a decompression chamber (simulated altitudes of 4 300 and 5 000 m) Ppa was obtained at 1 h of exposure to each simulated altitude.
  
  
  RESULTS
  Ppa in the pikas after the 4 300 m and 5 000 m altitude exposed did not significantly increase whereas in the rats Ppa rose significantly. The ratio of right ventricular to left ventricular plus septal weight in the pikas and rats was 0.22 and 0.45 respectively. The pikas maintained levels of Hb, hematocrit and 2.3-diphosphoglycerate lower than those of the rats. The percent wall thickness of the small pulmonary arteries in the pikas and rats was 9.22 and 27.21%, respectively, and it was well correlated with the degree of Ppa in both groups. Mast cells were observed in the lung of the rats (7.1 +/- 0.33 cells/mm2) but not in the pikas, There was highly positive staining for mast cell tryptase around pulmonary vessels in the rats, whereas no demonstrable reaction was observed in the pikas.
  
  
  CONCLUSIONS
  The pika has adapted to high altitude by losing hypoxia pulmonary vasoconstriction and thin-walled pulmonary arterioles. In rats, mast cells may play an important role in the remodeling of pulmonary vessels by activating some growth factors.
authors.affiliation: Qing Hai Institute of High Altitude Medicine, Xining 810012, China.
authors.forename: Q H
authors.initials: QH
authors.lastname: Chen
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000531:Altitude; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D007793:Lagomorpha / Q000502:physiology*; D011651:Pulmonary Artery / Q000502:physiology*; D011652:Pulmonary Circulation / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar