The rats were sacrificed 24 h after their last exposure by a lethal
intraperitoneal injection of 200 mg/kg pentobarbital. Bronchoalveolar
lavage was performed by flushing 8 ml of saline two times
successively in the right lung through a cannula located in the main
bronchus. The liquid was then collected for subsequent bronchoalveolar
lavage fluid analysis, whereas an approximately 50 mg sample of
left lung was cut down for the lung wet-to-dry weight ratio
determination while the remaining tissue was fixed for histological
examination, especially for the measurement of airspace enlargement.