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Bovine Pulmonary surfaetant was obtained by endotracheal lavage oflungs from newly slaughtered calves fallowed by differential centrifugation.Lipidextracts of bovine surfactant contained 86.1±2.1% of phospholipids（（?）±SD）

1.8

±

1.1% of protein

and smaller amounts of cholesterol

fatty acids

glyceridesand carbohydrate.Phosphatidylcholine（83.4±5.6%）accounted for most of thephospholipids

of which disaturated pbosphatidylcholine was 76.0±4.7%.Thephysic（?）chemical properties of bovine sarfactant were measured with a modifiedWilhelmy film balance made by the authors.The minimum surface tension was2.4±1.5mN/m

stability index 1.78±0.15.surface eompressibility at 10mN/m0.022±0.004m/mN

and surface concentration of phospholipids at 10 mN/m1.112±0.283 nmol/cm

2

.The surfactant spread rapidly and could be quicklyadsorbed to the air liquid interface.The results show that the bovine pulmonarysurfactant we isolated is able to meet the criteria for investigations of surfactantreplacement therapy.