[Effect of polycythemia on hypoxia induced pulmonary hypertension and pulmonary vascular remodeling in rats].
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.
Zhou
Yan-Rong
YR
Department of Pediatric Cardiology, West China Second Hospital, Sichuan University, Chengdu 610041, China.
Zhou
Tong-Fu
TF
Ouzhuluobu
Qiao
Li-Na
LN
Wang
Xiao-Qin
XQ
Xu
Hong-Bo
HB
Liu
Han-Ming
HM
Hua
Yi-Min
YM
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
D004921:Erythropoietin