Improvement of Lung Compliance during Postnatal Adaptation Correlates with Airway Sodium Transport

Abstract

Fetal lung liquid secretion is coupled with chloride transport into the lung lumen. The postnatal clearance of lung liquid is dependent on osmotic force generated by active sodium absorption. To study the interaction between airway epithelial sodium transport and postnatal lung function. We determined lung compliance and nasal transepithelial potential difference as a measure of airway ion transport and epithelial sodium channel gene expression in 41 healthy newborn infants during the first 50 h after birth. Lung compliance improved significantly during the study period, whereas nasal potential difference remained constant. There was a significant decrease in the expressions of beta and gamma subunits of the epithelial sodium channel. A positive correlation existed between amiloride-sensitive nasal potential difference measured at 1-4 h of age and lung compliance at 21-27 h of age. We found no correlation between the molecular data and functional measurements. An important part of pulmonary adaptation takes place during the first hour after birth. The improvement of lung compliance continues over the first postnatal days and coincides with down-regulation of epithelial sodium channel beta and gamma subunit expression.