Effects of a two-year inhalation exposure of rats to coal dust and/or diesel exhaust on tension responses of isolated airway smooth muscle.
Fedan-JS; Frazer-DG; Moorman-WJ; Attfield-MD; Franczak-MS; Kosten-CJ; Cahill-JF; Lewis-TR; Green-FH
Am Rev Respir Dis 1985 Apr; 131(4):651-655
The effects of inhalation exposure to coal dust and diesel exhaust were examined in Fischer-344-rats. Animals were exposed in inhalation chambers to filtered air, coal dust, diesel exhaust, or coal dust mixed with diesel exhaust for 7 hours per day, 5 days per week, for 2 years. Exposures to coal dust alone were at 2.0 milligrams per cubic meter (mg/m3). Exposure to diesel exhaust alone was at the same concentration. The composition of the coal dust and diesel exhaust mixture was 1mg/m3 of each agent. Changes induced with unspecified doses of acetylcholine (51843), 5- hydroxytryptamine (50679), potassium-chloride (7447407), and isoproterenol (7683592) were evaluated in-vitro on preparations of rat airway smooth muscle. Exposure of the rats to coal dust and diesel exhaust modified the pharmacologic responsiveness of the tracheal smooth muscle. The alterations were agonist specific and treatment dependent. Dark patches, less than 0.5 millimeter, were noted in the interstices between the cartilage of many of the animals treated with these agents. No patches were noted in the tracheas of the untreated rats. The patches were noted with the following frequencies: 80 percent from coal dust; 60 percent from diesel exhaust; and 60 percent from coal dust and diesel exhaust mixture. Coal dust or diesel exhaust exposures alone increased the maximal response to isoproterenol, but not significantly. The inhalation of both agents together resulted in a significantly larger maximal relaxation response than was observed in the controls. The maximal responses to acetylcholine of trachea from exposed rats were increased significantly compared with controls. Maximal responses to 5-hydroxytryptamine were not affected by any exposure. Concentration response relationships for potassium- chloride were not altered significantly. The authors conclude that coal dust and diesel exhaust interact to modify responsiveness to isoproterenol.
NIOSH-Author; Medical-research; Animal-studies; Industrial-dusts; Airborne-particles; Respirable-dust; Diesel-emissions; Comparative-toxicology; Mineral-dusts; Toxicology; Quantitative-analysis
51-84-3; 50-67-9; 7447-40-7; 7683-59-2
American Review of Respiratory Disease