Surfactant in Newborn Compared with Adolescent Pigs

Surfactant composition and function differ between vertebrates, depending on pulmonary anatomy and respiratory physiology. Be- cause pulmonary development in pigs is similar to that in humans, we investigated surface tension function, composition of phospho- lipid molecular species, and concentrations of surfactant protein (SP)-A to -D in term newborn pigs (NP) compared with adolescent pigs (AP), using the pulsating bubble surfactometer, mass spectrometry, high-performance liquid chromatography, and immunoblot tech- niques (IT). NP was more potent than AP surfactant in reaching minimal surface tension values near zero mN/m. Whereas SP-A and SP-D were comparable, SP-B and SP-C were increased 3- to 4-fold in NP surfactant. Moreover, fluidizing phospholipids such as palmi- toylmyristoyl-PC (PC16:0/14:0) and palmitoylpalmitoleoyl-PC (PC16: 0/16:1) were increased at the expense of PC16:0/16:0 (32.4 0.6 versus 44.5 3.2%, respectively). Whereas concentrations of total anionic phospholipids were similar in NP and AP surfactant (9.9 0.3 and 12.0 0.3%, respectively), phosphatidylinositol was the predominant anionic phospholipid in NP surfactant. We conclude that, compared with AP, NP surfactant displays better surface ten- sion function under dynamic conditions, which is associated with increased concentrations of SP-B and SP-C, as well as fluidizing phospholipids at the expense of PC16:0/16:0.