Accentuation of paraquat-induced toxicity by L-carnitine in mice

The effects of L-carnitine on toxicity induced by paraquat (PQ) in mice were investigated. L-carnitine pretreatment surprisingly promoted the toxicity of PQ in a dose-dependent manner shortening the survival time. The maximum effect occurred when L-carnitine, at a dose of 16 mmol/kg, was intraperitoneally administered 30 min before an intraperitoneal injection of PQ (75 mg/kg). Lipid peroxidation in lung significantly increased 6 h after PQ administration. L-carnitine accelerated this effect since L-carnitine-pretreated mice already showed a significant increase of lung malondialdehyde 1 h after PQ administration. In liver, PQ administration did not produce lipid peroxidation; nevertheless L-carnitine-pretreated mice showed a significant increase of malondialdehyde 6 h after PQ administration. Lung and liver glutathione decreased in mice receiving only PQ but this effect was not significantly changed by L-carnitine pretreatment. These results indicate that L-carnitine accelerates PQ-induced mortality rate by facilitating lipid peroxidation.