Effect of time in culture on modulation of Na(+)-K(+)-ATPase activity in rat alveolar type II cells

To determine the effect of time in culture on epithelial cell function, we evaluated the modulation of Na(+)-K(+)-ATPase activity in rat alveolar type II cells in culture. Ouabain sensitivity testing revealed that the alpha-1 predominance in the enzyme's isoforms was maintained over the 120 hours in culture. Basal Na(+)-K(+)-ATPase activity in the whole cell homogenate did not differ significantly between cells cultured for 48 hours and those cultured for 120 hours. Terbutaline (10 mM) did not activate Na(+)-K(+)-ATPase in the cells cultured for 48 hours, but, it significantly increased the activity of this enzyme in the cells cultured for 120 hours cells cultured for 48 hours, produced intracellular cyclic AMP after exposure to 10 mM of terbutaline. These results indicate that the coupling between Na(+)-K(+)-ATPase and the beta-adrenergic pathway in alveolar type II cells can be influenced by the time in cell culture.