title: Metabolism of lecithin and phosphatidylglycerol in surfactant fraction of the lung.
abstract: The metabolisms of lecithin and phosphatidylglycerol in the surfactant and residual fractions of rat lung were compared using the in vitro system where tissue slices and radioactive precursors such as [14C]palmitic acid, [14C]palmitoyl lysolecithin and [14C]stearoly lysolecithin were inculbated. The incorporation of precursors into the residual lecithin proceeded linearly during the incubation time, while the time curve on the incorporation into the surfactant lecithin exhibited a lag period before the incorporation increased significantly. A similar tendency was also observed in the incorporation into phosphatidylglycerol. These findings suggested a precursor-product relationship between the corresponding lipids in both the fractions. The turnover time of lecithin was approx. 340-370 min and that of phosphatidylglycerol was 118 min in the intracellular surfactant fraction. The turnover rates of lecithin and phosphatidlyglycerol were approx. 0.6 and 2 nmoles/g of wet tissue, respectively. The transfer of lecithin from the residual fraction to the surfactant fraction was hardly influenced by the difference of fatty acid moiety at the 2-position of 1-palmitoly-lysolecithin. However, the turnover time of 1-palmitoyl lecithin (360 min) was distinctly shorter than that of 1-stearoly species (730 min). The turnover time of the saturated lecithin was also shown to be 328 min. On the other hand, polyenoic species showed the shorter turnover time; 182 min for the tetraenoic species.
mesh_terms: D000818:Animals; D066298:In Vitro Techniques; D008168:Lung / Q000378:metabolism*; D008297:Male; D008954:Models, Biological; D010169:Palmitic Acids / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism*; D010715:Phosphatidylglycerols / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D011663:Pulmonary Surfactants / Q000378:metabolism*; D051381:Rats; D013229:Stearic Acids / Q000378:metabolism
chemical_list: D010169:Palmitic Acids; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D010743:Phospholipids; D011663:Pulmonary Surfactants; D013229:Stearic Acids