Figure 6.

Resistance to surfactant inhibition and effects on the ultrastructure of Survanta. (A) Surface tension was measured by a captive bubble surfactometer. Survanta (+ buffer) had high surface activity and minimum surface tension was low and was not influenced by addition of recombinant human surfactant protein D (rhSP-D). Plasma protein inhibited surface tension–lowering properties of Survanta and minimum surface tension was increased. The addition of rhSP-D rendered the Survanta more resistant to plasma protein inhibition. Minimum surface tension was low in the presence of plasma protein. n = 3, *P < 0.05 versus Survanta + buffer with plasma. (B, C) Representative electron micrographs of Survanta mixed with buffer or rhSP-D. Addition of rhSP-D changed ultrastructure of Survanta from simple lipid layers to the mixture of multiple lipid layers and lipid aggregates. n = 3 per group. Scale bar: 500 nm.