Changes in alveolar lavage materials and lung microsomal xenobiotic metabolism following exposures to HCl-washed or unwashed crystalline silica.
Miles-PR; Bowman-L; Jones-WG; Berry-DS; Vallyathan-V
Toxicol Appl Pharmacol 1994 Dec; 129(2):235-242
A comparison was made of the effects of the intratracheal instillation of two forms of crystalline silicon-dioxide (14808607) (unwashed and washed with hydrochloric-acid) and alumina (1344281) in male Sprague-Dawley-rats. The animals were sacrificed 2 weeks after exposure; lungs and trachea were removed for bronchoalveolar lavage and preparation of lung microsomes. Alveolar lavage phospholipids and proteins were assayed according to standard procedures while the xenobiotic metabolism was measured by luminescence spectroscopy. A comparison of the effects of the native silica and the washed silica showed a 1.3 versus 2.2 times increase in lung weights; a 25.9 versus 3.7 increase in lavage phospholipids; an 11 versus 3 times increase in alveolar lavage proteins; a 1.6 times increase for both in the concentration of microsomes; and a 4 versus 2 times increase in the total amount of pulmonary microsomal tissue. Instillation of the alumina resulted in a 1.15 times increase in lung weights, a 1.6 times increase in lavage phospholipids, and no significant effects on alveolar lavage proteins or microsomal tissue levels. Exposure to the washed silica resulted in a 2.3 times increase in 7-ethoxyresorufin-O-deethylation and a 0.5 to 0.6 times decrease in 7-ethoxycoumarin-O-deethylation. Exposure to native silica and alumina showed no significant effects on either xenobiotic when results were expressed per milligram of microsomal protein. The authors suggest that washed silica should not be used for studies of occupational exposure to silica since it does not provoke the same response as the native silica. The difference in iron levels may account for the differences in activity.
NIOSH-Author; Laboratory-animals; In-vivo-studies; In-vitro-studies; Enzyme-activity; Acute-exposure; Silicon-compounds; Silicosis; Alveolar-cells; Aluminum-compounds; Metabolic-study; Lung-function; Cell-metabolism; Cellular-uptake
Toxicology and Applied Pharmacology