Amiloride-sensitive nasal potential difference is not changed by estradiol and progesterone replacement but relates to BPD or death in a randomized trial on preterm infants.

Postnatal replacement of placental estradiol (E2) and progesterone (P) in preterm infants may improve lung function, possibly mediated through enhanced epithelial Na(+) transport and alveolar fluid clearance. Preterm infants of <29 wk gestational age and <1000 g birth weight requiring mechanical ventilation within 12 h of birth were randomized to receive either 2.5 mg/kg E2 and 22.5 mg/kg P per day (E2/P), or vehicle placebo. Epithelial Na(+) transport was assessed in 29 infants by measuring total nasal potential difference (NPD) and amiloride-sensitive NPD (ASNPD) on postnatal days of life 1, 3, 5, and 7, and mean values of all four measurements were calculated. Bronchopulmonary dysplasia (BPD) was defined as need for supplemental oxygen (goal Sa(O2) 90%) or mechanical ventilation at 36 wk corrected postmenstrual age. Mean ASNPD was -6.5 +/- 2.8 mV in infants receiving E2/P and -6.1 +/- 2.6 mV in infants receiving placebo (not significant). NPD was -10.6 +/- 3.8 mV and -10.7 +/- 3.6 mV, respectively. The ASNPD was significantly higher in infants surviving without BPD (-7.1 +/- 2.5 mV) than in infants developing BPD or not surviving (-5.2 +/- 2.4 mV). In conclusion, ASNPD is not changed by postnatal replacement of E2 and P. Infants at high risk of developing BPD had lower ASNPD values in the immediate postnatal period.