NA+ K- ATPASE IN LOWER AIRWAY EPITHELIUM FROM CYSTIC-FIBROSIS AND NON-CYSTIC-FIBROSIS LUNG/

The basolateral Na+/K+ ATPase plays a critical role in sodium reabsorp tion across airway epithelium. Nasal epithelium shows increased Na+/K ATPase activity in cystic fibrosis (CF) but Na+/K+ ATPase has not bee n characterized in human lung epithelium or compared in CF and normal lung, We measured (3)[H] ouabain binding and Na+/K+ ATPase activity in human tracheal epithelium and compared Na/K ATPase activity in bronch ial epithelium in CF and control subjects. In tracheal epithelium Na+/ K+ ATPase pumps were abundant and of high (3)[H] ouabain affinity (Kd 4.7 nM, B-max 38 pmol/mg) and Na+/K+ ATPase activity was 55+/-8 nmol/m g protein/min, Bronchial epithelial Na+/K+ ATPase activity was twofold higher in CF patients than in controls. The increased Na+/K+ ATPase a ctivity may contribute to the increased sodium reabsorption seen in cy stic fibrosis. (C) 1997 Academic Press.