Low pulmonary expression of epithelial Na(+) channel and Na(+), K(+)-ATPase in newborn infants with congenital diaphragmatic hernia.

It has been suggested from several animal studies and clinical observations that congenital diaphragmatic hernia (CDH) with pulmonary hypoplasia is accompanied by a disturbed perinatal ion transport. This could lead to respiratory distress due to slower clearance of fetal lung fluid at birth. The purpose of this study was to determine whether CDH is related to changes in the expression of three rate-limiting transporter proteins in lung epithelium at birth. Tracheal aspirate was collected from 12 newborn infants with CDH and from 8 newborn control patients. Sampling was performed at postnatal age 18 and at 43 h in the CDH group and at 18 h in the control group. The protein abundance of α-, β- and γ-epithelial Na(+) channel (ENaC), aquaporin 5 and Na(+), K(+)-ATPase α(1) was analyzed using semiquantitative immunoblotting. The levels of β-ENaC, γ-ENaC and Na(+), K(+)-ATPase α(1) collected at 18 h postnatally were significantly lower in CDH infants compared to control infants. In the CDH group, no significant difference in the expression of the ENaC subunits, Na(+), K(+)-ATPase α(1) or aquaporin 5 could be detected between the two sampling time points. This downregulation may result in an abnormal lung fluid absorption which could be an important mechanism behind the respiratory distress seen in newborn CDH patients.