Physical, chemical, and physiological characteristics of isolates of pulmonary surfactant from adult rabbits

Abstract

Physical and chemical characteristics of two types of preparations of surface active material from adult rabbits were determined. A procedure using multiple centrifugations produced a surface active material (type A) which had 6.6% by weight protein and a phosphorus/protein ratio of 13.1 nmol P/μg protein. A simpler protocol involving two centrifugations yielded a surface active material (type B) with more protein (10.8%) and a lower phosphorus/protein ratio (8.4 nmol/μg). Lipid compositions of both types were similar with phosphatidylcholine being the major phospholipid (80%) and palmitate the major fatty acid in the total lipid (65–71%) and in phosphatidylcholine (80%). Both types exhibited broad thermotropic phase transitions encompassing 37 °C. Measurements of aqueous dispersions of surface active material on the surface of a Langmuir–Wilhelmy balance or in a pulsating bubble apparatus indicated that there was variability both between types and between batches of the same type in the capacity to reach low surface tension on the surface balance and in the rates at which low surface tension was achieved on the bubble apparatus. Type A preparations were somewhat more reliable in meeting these ends than were type B. Both types of isolates were effective in normalizing pressure–volume characteristics when instilled into the lungs of immature rabbit fetuses.