Alterations in bronchoalveolar lavage constituents, oxidant/antioxidant status, and lung histology following intratracheal instillation of respirable suspended particulate matter.

Urban suspended particulate pollutants differ with place of occurrence, meteorological conditions, physicochemical compositions, and the response of the bronchopulmonary apparatus. Lung injury following intratracheal instillation of respirable suspended particulate matter (RSPM) collected in an urban setting in India was investigated in rats. The animals were killed 15 days after exposure to 2.5, 5.0, and 10.0 mg of RSPM. We examined the changes in lung histology, enzymatic activity in the bronchoalveolar lavage (BAL), and the oxidant/ antioxidant status in lung homogenates. The alterations in these parameters were compared with those in rats instilled with quartz particulates, which were used as positive controls. Exposure to RSPM resulted in an increase in the relative weight of lungs and inflammatory changes evidenced by an increase in the total cellularity of the lungs, predominantly polymorphonuclear cells, demonstrable both in the lungs sections and in the bronchoalveolar lavage of the exposed animals. An increase in the protein content and in the lactate dehydrogenase activity in the BAL was found in the RSPM-exposed rats. A marked increase in the output of lipid peroxides and a dose-dependent increase in the formation of reactive nitrogen species (NO) in lung homogenates and BAL, respectively, was found in the RSPM-exposed rats. A significant decrease in the enzymatic lung antioxidants, superoxide dismutase, and catalase was observed. However, the alterations in the levels of glutathione in the lungs of the RSPM-exposed animals were not significant. The inflammatory reaction, oxidative changes, and enzyme release, were more marked in quartz-exposed animals in comparison to the RSPM-exposed rats.

Immunotoxicity of soluble and insoluble salts of cadmium instilled intratracheally.

Rats were intratracheally (i.t.) exposed to 36.5 or 27.5 microg of cadmium (Cd) as soluble cadmium chloride (CdCl2) and insoluble cadmium oxide (CdO) salts. The retention of metal in lungs, liver and kidney was assessed by atomic adsorption spectrophotometer. The animals were intraperitoneally (i.p.) primed with sheep red blood cells (SRBC) and assessed for the number of antibody forming cells in lung associated lymph nodes (LALN) and spleen. Both the compounds had similar retention of metal in lungs but CdO induced more pulmonary inflammatory and degradative changes than CdCl2. The larger influx of polymorphonuclear cells (PMNs) following CdO exposure appears to be due to the absence of protection afforded by Cd induced metallothionein cytoplasmic protein while the Cd metallothionein complex formed in the case of CdCl2 is more protective. However both forms of Cd had similar local immunosuppressive potential but CdO had more prolonged suppressive effect.