Long-term exposure to ultrasonically nebulized distilled water and saline causes cellular influx and oxidative stress in lung tissue of rats.

ABSTRACT

PURPOSE: The aim of this study was to evaluate of the effect of distilled water and saline ultrasonic nebulization on the inflammatory and oxidative stress responses and on the lower airway architecture. MATERIALS AND METHODS: Twenty-one male Fischer rats were distributed into 3 groups of 7 animals each a control group (CG), exposed to ambient air; a saline group (SG), exposed to 0.9% sodium chloride (NaCl); and a group exposed to distilled water (DWG). The exposure was carried out in a box attached to an ultrasonic inhaler, occurring for 20 min, 3 times a day for 6 months. At 24h after the last exposure, the animals were euthanized. The bronchoalveolar lavage fluid (BALF) and lungs were collected for study. RESULTS: There was an increase of inflammatory cells in the pulmonary tissue BALF in the DWG compared with the CG. The DWG showed an increase of inflammatory cells compared with the SG and CG. The DWG and SG had higher NADPH oxidase activity than the CG. The volume density (Vv) of the alveolar septum was higher in the DWG than in the SG and CG, and the DWG also had a higher Vv of collagen fibers than the other 2 groups. The DWG presented elevated content of thiobarbituric acid reactive substances in lung homogenates relative to the SG and CG. CONCLUSIONS: The ultrasonic nebulization of distilled water increased the influx of inflammatory cells and oxidative damage, and promoted changes in the lung architecture.