ABSTRACT
Fibronectin (FN) is a major extracellular matrix glycoprotein, highly expressed in developing rat lungs. Several observations suggest that it play an important role in many developmental processes of animals. In vitro, FN can affect the adhesion, migration, proliferation, differentiation, and even apoptosis of various cell types. This study was undertaken to describe the distribution and localizations of fibronectin in the alveolar septum of lungs and liver lobules after CS gas exposure to experimental rats. The experimental rats (Sprague-Dawley strain), weighing 150~200 gm were sacrificed at 6 hours, 12 hours, 24 hours, 48 hours and 72 hours after CS gas exposure. The specimens of lung and liver were prepared for fibronectin immunoreactions of alveolar septa and liver lobules on experimental group, and for fibronectin reactions on the cytoplasm of type I alveolar cells, type II alveolar cells, fibroblasts, alveolar macrophages and interstitium in alveolar septa of lungs. All of specimens for immune reactions were observed with light and electron microscopes. The results obtained were as follows. 1. The liver lobules showed mild fibronectin reactions at the 6 hours and 12 hours after CS gas exposure. 2. The alveolar macrophages revealed strong fibronectin reactions. But alveolar septa showed weak FN reactions at 6 hours after CS gas exposure. 3. At 12 hours and 24 hours after CS gas exposure, the interstitial pneumonitis were seen in the lung alveoli. The gold particles were increased in the cells of alveolar septa, weak fibronectin reactions were revealed in the alveolar septum. 4. At 48 hours and 72 hours after CS gas exposure, FN reactions of alveolar septa were moderate, and the gold particles in the alveolar cells were markedly decreased. These results suggest that CS gas exposure to rats induces the increase of the fibronectin in lung and liver.