The Composition of Glycosaminoglycans in Developing Rabbit Lungs

Abstract

The components of connective tissue of the lung, fundamentally important to pulmonary function, undergo changes during development of the lung. In an effort to understand connective tissue macromolecular changes, glycosaminoglycans (GAG) were isolated from the lungs of rabbits of various ages, newborn to 24 weeks old. The concentration of total GAG was 15% greater in the lungs of 1-week-old rabbits than in the lungs of newborns. The total GAG concentration gradually decreased between 1 week and 12 weeks of age from 4.2 mg/g dry-defatted tissue to 1.5 mg/g dry-defatted tissue, and then reached a plateau. The predominant GAG in the lungs of newborn and 1-week-old rabbits were hyaluronic acid and chondroitin 4-sulfate. These GAG decreased with age while other GAG, particularly chondroitin 6-sulfate, increased. Analyses of heparan sulfate fractions from lungs of rabbits of various ages showed a microheterogeneity in the molecule. Increase in sulfation of heparan sulfate was observed with age. The observation suggests that not only the total concentration of GAG alters with age but individual GAG with specific physiologic functions also vary with growth and development of the lung.