Abstract

MARTINEZ MONTANO, María del Lurdez Consuelo; MUNOZ SANCHEZ, José Luis  and  BAEZA RAMIREZ, Isabel. Molecular association and function of calf lung surfactant. Acta bioquím. clín. latinoam. [online]. 2007, vol.41, n.2, pp.237-245. ISSN 0325-2957.

Surfactant, a highly surface-active material composed of phospholipids, neutral lipids and proteins, lines the lungs' alveolar surface facilitating alveolar ventilation. The molecular organization of surfactant components isolated from calf-lungs was analyzed by differential-scanning calorimetry and dynamic light-scattering, and subsequently compared to surfactant components organized in uni and multilamellar liposomes. The respiratory distress syndrome developed in adult guinea pigs was used for assessing surfactant activity. Calorimetry studies showed that lipid-protein interactions were considerably abated in native surfactant as compared to those of surfactant in uni or multi-lamellar liposomes. Light-scattering experiments indicated that native surfactant has a fibrillar shape with limited lipid-protein interactions, suggesting that it is organized in a lattice-like structure forming a stable film. These findings underscore the importance of the native molecular organization of surfactant. When surfactant reconstituted as uni- or multilamellar liposomes was administred to animals under respiratory distress, they did not recover. In contrast, when native surfactant was used to treat sick animals, arterial pH and PaCO₂ values improved, almost reaching normal values. It is important to emphasize that fewer steps in the protocol for isolation of calf lung surfactant made it possible to obtain it in a physiologically active molecular form.

Keywords : calf lung surfactant; multilamellar liposomes; unilamellar liposomes; respiratory distress syndrome; differential scanning calorimetry; light scattering.

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