Catabolism of rat surfactant disaturated phosphatidylcholines during incubation of alveolar lavage materials in vitro at 37 degrees C.
Incubation of rat alveolar lavage materials in vitro at 37 degrees C results in degradation of the endogenous surfactant disaturated phosphatidylcholines (disaturated PC). When exogenous dipalmitoylphosphatidylcholine (DPPC) vesicles are incubated with lavage materials, there is catabolism of the DPPC. The degradation process is temperature- and Ca2+-dependent and has a pH optimum of 6.5-7.0. The products formed during catabolism of [3H]palmitate- and [14C]choline-labeled disaturated PC are free palmitate and water-soluble choline products. No lysophosphatidylcholines are formed. Measurements of lactate dehydrogenase levels in lavage fluid, use of more gentle lavage techniques, use of Ca2+, Mg2+ and protein in the lavage medium, and measurements of bacterial contamination all suggest that enzymes are neither released into pulmonary lavage fluid via cellular damage nor are bacterial in origin. Degradation of surfactant disaturated PC does not occur during incubation of lavage materials from rabbits, mice or guinea pigs. These results suggest that phospholipases and/or lysophospholipases are present in rat alveolar lavage materials. Possible origins of these enzymes are discussed.
D000818:Animals; D002470:Cell Survival; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008297:Male; D010713:Phosphatidylcholines / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000032:analysis* / Q000166:cytology; D011663:Pulmonary Surfactants / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013696:Temperature; D007507:Therapeutic Irrigation; D013997:Time Factors
D010713:Phosphatidylcholines; D011663:Pulmonary Surfactants; D007770:L-Lactate Dehydrogenase