Objective: To investigate the antagonistic efficacy of tetrandrine (TET) on lung injury induced by acute paraquat poisoning.
Methods: Male Wistar rats were randomly divided into three groups (control group, non-treatment group and treatment group). The tetrandrine of 30 mg/kg was given by gastric lavage six hours after 32 rats were intraperitoneally injected with paraquat 15 mg/kg (treatment group). Then the same dose of tetrandrine was given once a day. Normal saline of the same volume was given by gastric lavage in another 32 rats intraperitoneally injected with paraquat 15 mg/kg (non-treatment group). Seven rats were intraperitoneally injected by normal saline as the control group. Levels of maleic dialdehyde (MDA), activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in plasma and the lung homogenate of three groups were determined at 3 d, 7 d, 14 d and 21 d after exposure to paraquat. Histological changes of the lungs were observed.
Results: The levels of MDA at 3 d both in plasma [(3.65 +/- 0.44) nmol/ml] and the lung homogenate [(9.54 +/- 0.92) nmol/mg pro] of the non-treatment group significantly increased compared with the control group (P < 0.01), the activities of GSH-Px and SOD in plasma at 3 d were significantly less than the control group (P < 0.05 or P < 0.01), the activities of GSH-Px (3 d, 7 d) and SOD (7 d, 14 d) in the lung homogenate were significantly less than the control group (P < 0.05). There were no significant difference in the levels of MDA both in plasma and the lung homogenate between the treatment group and the non-treatment group (P > 0.05). The SOD activities of treatment group on the third day was significantly increased compared with the non-treatment group (P < 0.01 or P < 0.05). Although the activities of GSH-Px in plasma and the lung homogenate of the treatment group on the third day were increased, there was no significantly difference compared with the non-treatment group (P > 0.05). The integral score of pulmonary fibrosis in the treatment group were significantly lower than in the non-treatment group (P < 0.01).
Conclusion: TET has antagonistic effect against acute toxicity of paraquat through significant reduction of pulmonary fibrosis.