Changes in alveolar capillary formation in growing rat lung by repeated injections of a lathyrogen.

We hypothesized that abnormal capillary formation, which might be associated with an alteration in extracellular malular matrix (ECM), occurs in the alveoli of growing rat lungs treated with beta-aminopropionitrile (beta APN), a lathyrogen that inhibits lysyl oxidase activity. On scanning electron microscopy, a corrosion cast of alveolar capillaries in lungs treated with beta APN appeared abnormal in configuration; transmission electron microscopy showed extensive morphological changes in interstitial cells and ECMs, including collagen, elastin, and presumably glycosaminoglycans and, in binding water (GBW). Morphometric data revealed an increase in GBW of up to 24.4%, a decrease in the amount of collagen fiber (44.5%), and a decrease in lipid-laden interstitial cells; however, the change in elastin was limited to morphological appearance. From these observations, we conclude that alterations in alveolar capillary formation are associate with extensive changes in ECMs, and that these changes in ECM components might also be involved in the abnormal alveolar formations induced by beta APN.