Biochemical and metabolic properties of bovine type II pneumocytes in primary culture

Bovine type II pneumocytes were isolated from lungs of adult cattle by enzymatic tissue dissociation and subsequent purification by density gradient centrifugation on a 1.040 g/ml Percoll gradient. By quantitative and qualitative high-performance liquid chromatographic (HPLC) analysis of freshly isolated, highly purified bovine type II pneumocytes, six phospholipid components (phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and sphingomyelin) were detected regularly and their composition was compared to that of whole lung homogenates. Total phospholipid content of 10⁶ bovine type II cells was 34.7 µg (quantitative HPLC). Suspended and adherent bovine type II cells incorporated ¹⁴C]choline into their phospholipids. The rate of synthesis of suspended cells (289 pmol/h×10⁶ cells) was constant for at least 4 h, while adherent type II cells incorporated ¹⁴C]choline with a constant rate of 160 pmol/h×10⁶ cells for at least 20 h. These data further establish the use of cultured bovine type II pneumocytes as a high-purity model for the in vitro investigation of the surfactant system.