Evaluation of the Content of Aquaporin-5 and Epithelial Sodium Channel in the Lungs of Rats during the Development of Toxic Pulmonary Edema Caused by Intoxication with Acylating Pulmonotoxicants.

We studied the content of aquaporin-5 (AQP5) and epithelial sodium channel (ENaC) in rat lungs during the development of toxic pulmonary edema (TPE) caused by intoxication with phosgene and perfluoroisobutylene (1.5 LC50). The lung body weight index (LBI) was calculated and histological examination of the lung tissues was performed. Localization and expression of AQP5 and ENaC were determined by immunohistochemistry. Intoxication led to a significant (p<0.05) increase in LBI and histological changes typical of TPE 1 and 3 h after the exposure. In 1 and 3 h after phosgene intoxication, the AQP5 and ENaC content significantly (p<0.05) increased in comparison with the control. Similar changes in the AQP5 and ENaC content were observed 1 and 3 h after exposure to perfluoroisobutylene. It was hypothesized that AQP5 plays an important role in the formation of TPE caused by intoxication with acylating pulmonotoxicants. An increase in the content of ENaC can be considered as a compensatory reaction of the body aimed at clearance of the alveolar fluid.

Ultrastructural Changes in the Air-Blood Barrier of Rats in Acute Intoxication with Furoplast Pyrolysis Products.

Rats were exposed to fluoroplast-4 pyrolysis products (sample weight 2.6 g, pyrolysis temperature 440-750°C, pyrolysis duration 4 min) containing perfluoroisobutylene over 15 min. Lung tissue samples for histological and electron microscopic examination were isolated in 3 and 30 min after intoxication and processed routinely. Histological examination revealed no structural changes in the lungs. In ultrathin sections of rat lungs, some changes in the structure of type I pneumocytes were detected in 3 min after the exposure: detachment of cytoplasmic processes and the appearance of transcytosis pores. These changes attested to impaired cell-cell interactions and their adhesion to the basement membrane, where structural disorganization and edema of the collagen matrix were observed. In 30 min following exposure, the signs of damage to type I pneumocytes became more pronounced. The increase in the equivalents of transcellular and paracellular permeability in the alveolar lining profile was observed. No changes in the pulmonary capillary endotheliocytes were detected, which suggest that type I pneumocytes are the primary target of the toxic effect of perfluoroisobutylene. The vulnerability of a particular cell population, in view of specific metabolism of these cells, can be the key to deciphering of the mechanisms of the toxic effect of pyrolysis products of fluorinated polymer materials.