Modulation of aquaporin 4 and the amiloride-inhibitable sodium channel in perinatal rat lung epithelial cells

During the perinatal period, a dramatic reversal of lung transepithelial ion and water transport occurs that involves the amiloride-inhibitable Na+ channel (ENaC). Aquaporin (AQP) water channel proteins facilitate cell membrane water transport. We now report that AQP-4, localized to basolateral membranes of airway epithelial cells, increases its mRNA expression in developing lung eightfold during the 2 days before birth to reach a peak on the first postnatal day in the lungs but not in brains or kidneys of neonatal rats.