Modulation of Biochemical and Cytological Profile of Bronchoalveolar Lavage Constituents in Rats Following Split-Dose Multiple Inhalation Exposure to Methyl Isocyanate

1 Studies were carried out to explore the acute pulmonary effects of equal, split-dose, multiple inhalation exposures of rats to methyl isocyanate (MIC), (0.32 mg l ^-1, 8 min x 10 exposures) as reflected by alterations in bronchoalveolar lavage fluid (BALF) constituents and to evaluate recovery, if any, following survival in a MIC-free environment, 10 d after the last MIC exposure.

2 In the BALF of MIC-exposed rats, there was an increase in the total number of cells and the number of cells showing enhanced dye uptake and reduction of nitroblue tetrazolium chloride. The cell-free BALF showed increases in total protein, sialic acids and lactic acid contents and lactate dehydrogenase activity.

3 In rats exposed to MIC and sacrificed 10 d after survival in a MIC-free environment, there was a reduction in the cellular and biochemical constituents of BALF. The phagocytic potential of macrophages was, however, also decreased under this regime.