[Long-term effect of a beta-adrenergic agonist on sodium uptake into cultured rat alveolar type II cells]

To evaluate the long-term effect of a beta-adrenergic agonist on Na(+)-channel function in cultured rat alveolar type II cells, we measured 22Na+ uptake into type II cells cultured in the presence and absence of 0.1 mM terbutaline for up to 5 days. Terbutaline did not influence the growth, morphology, or protein content of the cells. Terbutaline increased amiloride-inhibitable 22Na+ uptake into the cells at day 2 in culture, but there was no significant difference at day 5. Because amiloride-inhibitable 22Na+ uptake reflects Na(+)-channel function, these data indicate that terbutaline may transiently upregulate Na(+)-channel function. This study provides direct evidence of a long-term effect of a beta-adrenergic agonist on Na(+)-channel function in alveolar type II cells.