Endogenous nitric oxide and endothelin-1 in persistent pulmonary hypertension of the newborn

We studied changes in endogenous nitric oxide (NO) synthesis and endothelin -l (ET-1) production in infants with persistent pulmonary hypertension of t he newborn (PPHN). We determined concentrations of serum NO metabolites, i. e., nitrites and nitrates (NOx), and of plasma ET-I in five infants with PP HN (PPHN group) and in 25 healthy full-term neonates (control group). In bo th groups, serum NOx concentrations increased over time and plasma ET-1 con centrations decreased with age. The differences in serum NOx concentrations between groups were not significant at < 12 h and 24 h of age; however, th ey were significantly higher in the PPHN group than in the control group at 5 days of age. The differences in plasma ET-1 concentrations between group s were not significant at 5 days of age, but were significantly higher in t he PPHN group than in the control group at < 12 h and 24 h of age. Conclusion Limited endogenous nitric oxide synthesis and elevated endogenou s endothelin-1 production during the first few days of life may contribute to pulmonary hypertension in infants with persistent pulmonary hypertension of the newborn.