Significance of ion transport during lung development and in respiratory disease of the newborn.
Active ion transport plays a critical role in the liquid movement across the fetal and perinatal lung epithelium. The fetal lung liquid production is coupled with active secretion of Cl- into the luminal space. The potential for fluid absorbing mechanisms related to active Na+ transport from the apical to the basolateral side of the epithelium appears near the end of gestation. At birth there is a dramatic change of environment with commencement of air-breathing, sudden increase in oxygen partial pressure (PO2) and profound changes in the pulmonary circulation. A concurrent switch from fluid secretion to maintenance of low amounts of alveolar fluid is another major physiological adjustment taking place in the perinatal distal lung epithelium. The fluid-absorbing mechanism is a result of a well-synchronized co-operation between the basolateral membrane Na-K-ATPase and the apical membrane Na+ channels and it promotes salt and water movement from the airspace. Inability of the fetal lung epithelium to switch from fluid secretion to Na+ transport-dependent absorption seems to be an important factor adversely contributing to the respiratory distress of the newborn premature infant.
Pitkänen
O M
OM
Hospital for Children and Adolescents, University of Helsinki, Finland. olli.open@netlife.fi
O'Brodovich
H M
HM
D004848:Epithelium / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D017136:Ion Transport; D008168:Lung / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D012127:Respiratory Distress Syndrome, Newborn / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
D012964:Sodium