Lipid peroxidation in the membrane damaging effect of silica-containing dust on rat lungs

Rats were injected intratracheally with a single dose of 50 mg silica (DQ-12) suspended in 0.5 ml saline. The animals were sacrificed at 3, 6, 12 and 21 days following exposure, and the rate of lipid peroxidation as well as the activities of superoxide dismutase and catalase were measured in the lung tissue. Parallelly the redox state potential of the lung tissues was also determined during this period. It was found that under the effect of silica, lipid peroxidation gradually increased in the lung. This effect was accompanied by enhancement of superoxide dismutase and catalase activity. The redox state potentials were shifted to oxidation. It is suggested that silica, though indirectly, induces free radical production associated with oxidosis, which, through lipid peroxidation, increases to membrane injury.