Fig. 2.

Surfactant protein-B (SP-B) inhibits Group IB sPLA₂ hydrolysis of Survanta and pure PL vesicles. Group IB sPLA₂ hydrolysis of PG (A) and PC (B) were measured in Survanta vs. Survanta supplemented with 1% SP-B, and in PL vesicles (PL mix) containing dipalmitoylphosphatidylcholine (DPPC), 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC), and 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) (DPPC:POPC:POPG, 40:40:20) labeled with either [H³]-PG (A) or [H³]-PC (B) and incubated with Group IB sPLA₂ (0.1–10 U/ml) at 37°C for 2 h. Hydrolysis of both surfactant substrates decreased in surfactant supplemented with SP-B. Data represent the means ± SD of ≥3 experiments. *P < 0.01 compared with surfactants without SP-B.