[Long-term effect of a beta-adrenergic agonist on Na+/K(+)-ATPase activity in rat lung explants]

To test the long-term effect of a beta-adrenergic agonist on Na+/K(+)-ATPase activity in rat lung explants, we measured the activity in lung explants kept continuously in the presence or absence of 0.1 mM terbutaline for 5 days. Once it was clear that this agent increased Na+/K(+)-ATPase activity, we then performed a similar measurement in cultured alveolar type II cells from rats. Continuous exposure to 0.1 mM terbutaline enhanced the enzyme activity in those cells, and this enhancement was completely blocked by 0.01 mM of the beta-antagonist propranolol. Western blotting showed that this increase in Na+/ K(+)-ATPase activity in the cells could involve modulation of protein expression. We conclude that beta-adrenergic agonists can increase Na+/K(+)-ATPase activity in alveolar type II cell in lung explants by modulating expression of the enzyme in a long period of time.