Biophysical and Physiological Properties of Synthetic Surfactants Containing a Surfactant Protein Analog

Abstract

Purpose: The in vitro biophysical and in vivo physiological properties of two synthetic surfactants containing either an SP-B or SP-C analog were compared with those of a modified bovine surfactant preparation, Surfactant-TA (Surfacten). Methods: Biophysical properties were measured using a modified Wilhelmy surface balance with reference to adsorption, spreading, minimum and maximum surface tension, and % trough area at 10 mN/m. Physiological properties were measured by recording pressure-volume curves using rabbit fetuses delivered prematurely. Rabbit fetuses were randomly assigned to receive one of the surfactants intratracheally. Premature littermates and term fetuses were used as controls. Results: The SP-C lipid mixture and Surfacten exhibited similar biophysical and physiological properties appropriate for a pulmonary surfactant, whereas the SP-B lipid mixture did not satisfy these criteria. Conclusions: The SP-C lipid mixture exhibited properties appropriate for a pulmonary surfactant, comparable to Surfacten. In contrast, the SP-B analog may not be an alternative to natural SP-B. Based on our study, clinical trials of surfactant containing the SP-C analog can be justified.