title: [Effect of polycythemia on hypoxia induced pulmonary hypertension and pulmonary vascular remodeling in rats].
abstract: OBJECTIVE
  To investigate the effect of polycythemia on hypoxia induced pulmonary hypertension and pulmonary vascular remodeling in rats.
  
  
  METHODS
  The healthy female Sprague-Dawley rats were randomly divided into 3 groups: normoxia control group (C group), hypoxia group (H group), hypoxia + different doses of human recombine hemopoietin (rEPO) group. All rats in hyoxia groups were exposed to hypoxia, 8 hours every day, for 21 days. The rEPO groups were injected sc with different doses of rEPO (300 U/kg, 600 U/kg, 900 U/kg, 1200 U/kg) thrice weekly. Blood samples were taken for the measurement of RBC, Hb, Hct, plasma EPO concentration, whole blood/plasma viscosities, the animals were then catheterized to record mean pulmonary arterial pressure (mPAP) and demised to calculate the ratio [RV/(LV+S)]. Percentage of vascular wall thickness and muscularization of non-muscular pulmonary arteriole were examined microscopically.
  
  
  RESULTS
  (1) As the dosage of exogenous rEPO increased, blood concentration of EPO increased correspondingly, as RBC, Hb, Hct and whole blood/plasma viscosities increased in various degrees. (2) There was positive correlation between whole blood viscosity and Hct at both high and low shears and linear correlation between mPAP and whole blood viscosity at high shear. (3) The degree of pulmonary hypertension, reflected by mPAP increased in accordance to rEPO dosage increment. However, the extent of pulmonary vascular remodeling alleviated somehow as the rEPO dose increased and so did right ventricular hypertrophy.
  
  
  CONCLUSIONS
  Polycythemia induced by exogenous EPO increases the blood viscosity and the pulmonary vascular resistance, which contributes to the formation of hypoxia induced pulmonary hypertension.
authors.affiliation: Department of Pediatric Cardiology, West China Second Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Yan-Rong
authors.initials: YR
authors.lastname: Zhou
authors.forename: Tong-Fu
authors.initials: TF
authors.lastname: Zhou
authors.lastname: Ouzhuluobu
authors.forename: Li-Na
authors.initials: LN
authors.lastname: Qiao
authors.forename: Xiao-Qin
authors.initials: XQ
authors.lastname: Wang
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Xu
authors.forename: Han-Ming
authors.initials: HM
authors.lastname: Liu
authors.forename: Yi-Min
authors.initials: YM
authors.lastname: Hua
mesh_terms: D000818:Animals; D004921:Erythropoietin / Q000494:pharmacology; D005260:Female; D006976:Hypertension, Pulmonary / Q000209:etiology / Q000503:physiopathology*; D000860:Hypoxia / Q000150:complications / Q000503:physiopathology*; D011086:Polycythemia / Q000503:physiopathology*; D011651:Pulmonary Artery / Q000503:physiopathology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004921:Erythropoietin