PLASMA-IMMUNOREACTIVE ENDOTHELIN-1 CONCENTRATIONS IN INFANTS WITH PERSISTENT PULMONARY-HYPERTENSION OF THE NEWBORN

Plasma concentrations of endothelin-1 (ET-1) have been reported to be elevated in children and adults with pulmonary hypertension. We hypoth esized that infants with persistent pulmonary hypertension of the newb orn (PPHN) have elevated plasma concentrations of ET-1. Plasma concent rations of immunoreactive-endothelin-1 (ir-ET-1) were measured using a radioimmunoassay in 20 infants with PPHN and 20 normal term infants. Mean birthweight and gestational age of the infants were comparable in the two groups. The mean plasma ir-ET-1 concentrations were significa ntly elevated in neonates with PPHN compared to those of normal term i nfants (2.04 +/- 0.30 versus 1.04 +/- 0.29 pg/mL, p = 0.02). A linear regression analysis demonstrated a significant relationship between ir -ET-1 concentrations and alveolar-arterial oxygen gradient (r = 0.49, p = 0.02) and mean airway pressure (r = 0.49, p = 0.02). There was als o a significant correlation between ir-ET-1 concentrations and duratio n of extracorporeal membrane oxygenation among infants with PPHN (r = 0.44, p = 0.05). We conclude that plasma ir-ET-1 concentrations are el evated in infants with PPHN. The presence of elevated ir-ET-1 concentr ations and their positive correlation with disease severity suggests t hat ET-1 may serve as a marker of the disease severity in these infant s. However, further studies are needed to elucidate the role of ET-1 i n the pathophysiology of PPHN.