The effect of colchicine and vinblastine on the release of pulmonary surface active material

The secretion of phosphatidylcholine was studied by incubating hamster lung slices which had been prelabeled by the in vivo administration of 14C-labeled choline. The release of 14C-labeled phospholipid into the medium continued for 2 hr. The specific activity of phosphatidylcholine in the medium was one-third that found in the tissue, and the fatty acid composition of the released phosphatidylcholine corresponded to that of surfactant. The prior injection of colchicine resulted in a 60% inhibition of phosphatidylcholine release into the incubation medium. A similar effect was obtained when vinblastine was administered. Colchicine demonstrated no inhibiting effect on the release of protein from lung slices which had been prelabeled by the administration of 14C-labeled leucine. The possible function of the microtubular system in the secretion of surface active components is discussed.