Expression of water and ion transporters in tracheal aspirates from neonates with respiratory distress

Aim: The aim of the study was to determine whether neonatal respiratory distress is related to changes in water and ion transporter expression in lung epithelium. Methods: The study included 32 neonates on mechanical ventilation: 6 patients with normal lung X-rays (control group), eight with respiratory distress syndrome (RDS), eight with transient tachypnea of the newborn (TTN), 10 with abnormal lung X-rays (mixed group). The protein abundance of water channel AQP5, epithelial sodium channel (ENaC; alpha-, beta- and gamma-ENaC) and Na+, K+-ATPase alpha 1 were examined in tracheal aspirates using semiquantitative immunoblotting. Results: beta-ENaC level was significantly lower in RDS group compared with infants with TTN and infants in the control group. AQP5 expression was significantly higher in TTN compared with the infants with RDS and all other infants with abnormal lung X-rays. Conclusion: Neonatal respiratory distress is associated with changes in beta-ENaC and AQP5 expression. The lower beta-ENaC expression may be one of the factors that predispose to the development of RDS. The higher AQP5 expression may provide the possibility for reabsorption of postnatal lung liquid, which contributes to quick recovery of infants with TTN.