[Effects of erythromycin on surfactant synthesis, secretion, and recycling by rat alveolar type II cells]

Effects of erythromycin on surfactant synthesis, secretion, and recycling by rat alveolar type II cells were examined. Type II cells were isolated from rat lungs and incubated with 3H-choline, a precursor of surfactant. Synthesis was quantified from the amount of 3H-phosphatidylcholine and from the distribution to lamellar body fractions as measured with sucrose density gradients. Secretion was quantified from the percent of synthesized 3H-phosphatidylcholine released into the medium over 3 hr. Recycling was quantified from the percent uptake over 1 h of 3H-labeled synthetic liposomes. Type II cells incubated with erythromycin (5-50 micrograms/ml) for 22 hrs secreted less surfactant in response to PMA and ATP than did control cells. Erythromycin did not affect synthesis or recycling of surfactant by type II cells. These results show that erythromycin inhibits surfactant secretion from type II cells, and suggest that erythromycin may be effective in surfactant-excess states such as alveolar proteinosis.