Biochemical and morphological correlation of oxidant-induced pulmonary injury: low dose exposure to paraquat, oxygen, and ozone.

The authors compared the temporal pattern of low-dose oxidant-induced lung injury in rats after exposure to either 1 ppm ozone or 100% oxygen for 24 hr or from treatment with paraquat (20 mg/kg, intraperitoneally). Histological abnormalities in airways, parenchyma, and blood vessels were evaluated from coded and randomized sections and compared with appropriate controls. Drug metabolism by lung endoplasmic reticulum was studied in similarly treated rats as another index of lung injury. Exposure to oxygen caused no discernible morphological or biochemical abnormalities. Exposure to ozone caused histological lesions which appeared early and resolved by 7 to 14 days, whereas paraquat-induced lesions were first evident at about 7 to 14 days. Abnormalities in drug metabolism followed a similar pattern. Low-dose oxidant exposure from ozone and paraquat produce similar histological and biochemical lesions in rat lungs but with distinct temporal patterns.