Synthesis and secretion of plasmalogens by type-II pneumocytes.

摘要: Alveolar surfactant (exposed to air and therefore a prime target of oxidants) is supplied with antioxidants during its intracellular formation on type-II pneumocytes [Rustow, Haupt, Stevens Kunze (1993) Am. J. Physiol. 265, L133-L139]. Plasmalogens can protect animal cells against lipid peroxidation caused by u.v. radiation. It has been suggested that plasmalogens play direct role in protecting cell membranes oxidative stress [Zoeller, Morand Raetz (1988) Biol. Chem. 263, 11590-11596]. We investigated biosynthesis secretion phospholipids adult rat lungs. The consist 93% ethanolamine (EthPlas) 7% choline (ChoPlas). isolated from alveolar surfactant, however, 36.5% ChoPlas 63.5% EthPlas. different incorporation rates [14C]hexadecanol into both types plasmalogen are reflected the relative proportions their total cellular content. Type-II cultured presence labelled hexadecanol or hexadecylglycerol palmitate secrete phospholipids, spontaneously response isoprenaline. spontaneous stimulated 3-6 times higher than those This rate corresponds proportion content compared cells. Added extracellular surfactant-specific protein A inhibits as well molecular species EthPlas lung lavage do not differ significantly mainly containing poly-unsaturated fatty acids. conclude secreted partly integral constituents surfactant. select between for constituent intramolecular sorting signal presumably moiety.