The immediate and the late effects of inhaled Paraquat (PQ) on systemic and lung inflammation and oxidative stress were investigated. Rats were exposed to saline (control group) and two doses of inhaled PQ (27 and 54 mg/m3) and studied variables were measured: 1) one day after the end of PQ exposure as \\\\\\\"immediate condition\\\\\\\", 2) 16 days after the end of PQ exposure as \\\\\\\"late condition\\\\\\\". Total and differential white blood cells (WBC) counts, lipid peroxidation and nitrite were increased but thiol, superoxide dismutase and catalase in the blood and BALF as well as methacholine EC50 was reduced in both conditions in the animals exposed to PQ compared to control groups (p < 0. 05 to p < 0.001). Most studied parameters in the immediate condition were significantly higher than the late condition (p < 0.05 to p < 0.001). Systemic and lung inflammation and oxidative stress due to inhaled PQ in both the immediate and the late conditions were shown. Although most measured parameters in the immediate condition were higher, all variables were significantly different with the control group even in late condition, indicating a long-term effect of inhaled PQ toxicity, which may help in a more effective treatment of PQ poising in the future.

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