Lung surfactants. I. Comparison of surfactants prepared from lungs of calf, ox, dog and rabbit.

Abstract

Lung surfactants were extracted either by lavage or by mincing method from lungs of calves, oxen, dogs and rabbits, and were purified in parallel. These lung surfactants were modified by adding some components in which they were apparently deficient ; the contents of disaturated phosphatidylcholine, fatty acids and triacylglycerols were adjusted to 47, 7 and 7%, respectively. The native and modified lung surfactants were examined with respect to their surface properties in vitro and their lung pressure-volume characteristics in vivo. No obvious differences were found in the chemical components of the lung surfactants from different mammalian species and of those prepared by the different extraction methods. Although there were no distinct differences in the phosphatidylcholine contents of the lung surfactants among the mammalian species, the content in the samples obtained by the lavage method was slightly higher than that in samples obtained by the mincing method. Although all the native lung surfactants spread spontaneously and were rapidly adsorbed, they did not show good surface activities in vitro or good lung pressure-volume characteristics in vivo. In contrast, all the modified lung surfactants showed good surface properties in vitro and also gave normal lung pressure-volume characteristics to premature rabbit fetuses in vivo irrespective of the mammalian species from which the native surfactants had been derived or of the extraction method used.