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1209.19 |
1 Pediatrics, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA
2 Pediatrics, Los Angeles Biomedical Research institute at Harbor-UCLA Medical Center, Torrance, CA
ABSTRACT
Endogenous PAF contributes to high vasomotor tone in the fetal pulmonary circulation and has been implicated in the pathogenesis of chronic-hypoxia (CH)-induced pulmonary hypertension (PH). We studied the effect of CH on neonatal rat (pup) body weight, right ventricle/left ventricle + septum ratio (RV/LV+S), and lung PAF receptor (PAF-r) protein expression by Western blotting. Pups were placed in an air-tight chamber ventilated with 13% oxygen (hypoxia) or room air (normoxia) from 1d to 22d of age. Three groups were studied (12 pups in each group): Group1, pups in Hypoxia; Group2, pups in hypoxia given 5mg/kg WEB 2170 daily, a PAF-r antagonist, (Hypoxia +WEB); Group3, pups in Normoxia. We found that: a) Pups in Hypoxia gained 50% less weight than pups in Normoxia; WEB treatment in Hypoxia did not improve weight gain; b) RV/LV+S in Hypoxia group was highest at 0.79; 2-fold higher than in WEB + Hypoxia and Normoxia groups; c) PAF-r protein expression in lungs of pups in Hypoxia was >3-fold higher than in WEB+Hypoxia and Normoxia groups. Our findings show that chronic hypoxia induces PAF-r expression in lungs and suggest that increased PAF-r expression may be responsible for the right ventricular hypertrophy and PH. Inhibition of PAF effects with a PAF-r antagonist, WEB, though it did not improve weight gain of the pups in hypoxia, prevented RV hypertrophy in the pups. HL-077819.
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