Correlation between biochemical and morphological repair in rabbit lungs after elastase injury

The structural and elastic properties of the lung depend primarily on the concentration in connective tissue of proteins, collagen and elastin. The relationships between biochemical and morphological aspects of pulmonary damage were studied in 50 male New Zealand rabbit's, randomly divided into two groups of 25 animals, instilled with 245 IU of pig pancreatic elastase solution or physiological saline. Animals were killed at 8, 15, 30, 60 and 90 days after treatment. The changes in pulmonary morphology and in collagen and elastin content have been studied chemically and by light microscopy. The left lungs were used for biochemical determinations of insoluble elastin and total, insoluble and salt-extractable collagens. Morphometric measurements (mean linear intercepts or Lm) and histologic evaluations were performed on right lungs. Three months after instillation, the elastase treated lungs showed a minimal degree of alveolar wall rupture, and no significant difference in Lm from the control group. Quantitative restoration of normal biochemical parameters preceded connective tissue repair. Statistical evaluations showed significative correlations among Lm, total collagen (p < 0.01) and insoluble elastin/dry weight (p < 0.01). No significant differences between Lm and insoluble elastin, salt-extractable collagen or total collagen/dry weight were found. © 1980 Springer-Verlag.