FUNCTIONAL, BIOCHEMICAL, AND HISTOPATHOLOGICAL EVIDENCE OF AIRWAY-OBSTRUCTION IN RATS FOLLOWING A 4-HOUR ACUTE INHALATION EXPOSURE TO NORMAL-BUTYL ISOCYANATE

Pulmonary function, arterial blood gases, acid-base status, and bronchoalveolar lavage fluid (BALF) composition were assessed in male Wistar rats after a single 4-h exposure to 0, 7.6, 23.5 or 55.2mg n-butyl isocyanate (n-BIC)/m3 air. No significant changes other than transient clinical signs were observed in the rats exposed to 7.6mg/m3 air. Four weeks after exposure the animals of the 55.2mg/m3 group showed significant effects: those were pronounced histopathological changes of airways and parenchyma, and elevated relative lung weight. The neutrophils, LDH, and protein in BALF were elevated. Quasistatic lung compliance, peak expiratory flow rate, mean mid expiratory flow rate were decreased whereas lung resistance, residual volume, and single breath CO-diffusing capacity were increased. Blood gas measurements revealed an elevation in hemoglobin, pH, arterioalveolar oxygen difference, and venous admixture. Arterial pO2 and pCO2 were decreased. In animals exposed to 23.5mg/m3 only marginal effects were detectable.