Mechanical stretching of alveolar epithelial cells increases Na+-K+-ATPase activity

• Published in: Journal of applied physiology (1985) 1999-08, Vol.87 (2), p.715-721
• Main Authors: Waters, Christopher M, Ridge, Karen M, Sunio, G, Venetsanou, K, Sznajder, Jacob Iasha
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Amiloride - pharmacology; Animals; Biological and medical sciences; Biological Transport; Cell Line; Cell Membrane - metabolism; Cells; Enzymes; Epithelium - metabolism; Gadolinium - pharmacology; Lungs; Medical sciences; Mice; Nystatin - pharmacology; Pneumology; Potassium; Pulmonary Alveoli - metabolism; Pulmonary hypertension. Acute cor pulmonale. Pulmonary embolism. Pulmonary vascular diseases; Pulmonary Stretch Receptors - physiology; Rubidium - metabolism; Sodium; Sodium - metabolism; Sodium-Potassium-Exchanging ATPase - metabolism
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1999.87.2.715

1  Departments of Anesthesiology and Biomedical Engineering, Northwestern University, Chicago 60611; 2  Pulmonary and Critical Care, Michael Reese Hospital, University of Illinois at Chicago, Chicago, Illinois 60616; and 3  Agioi Anargyroi, Cancer Hospital of Kifisia, Athens, Greece Alveolar epithelial cells effect edema clearance by transporting Na + and liquid out of the air spaces. Active Na + transport by the basolaterally located Na + -K + -ATPase is an important contributor to lung edema clearance. Because alveoli undergo cyclic stretch in vivo, we investigated the role of cyclic stretch in the regulation of Na + -K + -ATPase activity in alveolar epithelial cells. Using the Flexercell Strain Unit, we exposed a cell line of murine lung epithelial cells (MLE-12) to cyclic stretch (30 cycles/min). After 15 min of stretch (10% mean strain), there was no change in Na + -K + -ATPase activity, as assessed by 86 Rb + uptake. By 30 min and after 60 min, Na + -K + -ATPase activity was significantly increased. When cells were treated with amiloride to block amiloride-sensitive Na + entry into cells or when cells were treated with gadolinium to block stretch-activated, nonselective cation channels, there was no stimulation of Na + -K + -ATPase activity by cyclic stretch. Conversely, cells exposed to Nystatin, which increases Na + entry into cells, demonstrated increased Na + -K + -ATPase activity. The changes in Na + -K + -ATPase activity were paralleled by increased Na + -K + -ATPase protein in the basolateral membrane of MLE-12 cells. Thus, in MLE-12 cells, short-term cyclic stretch stimulates Na + -K + -ATPase activity, most likely by increasing intracellular Na + and by recruitment of Na + -K + -ATPase subunits from intracellular pools to the basolateral membrane. sodium transport; amiloride; gadolinium; Nystatin; pulmonary edema; mechanical ventilation; sodium-potassium-adenosine 5'-triphosphatase