| Background Paraquat is the trade name for 1,1'-dimethyl-4,4'-bipyridinium dichloride,one of the most widely used herbicides in the world.Paraquat is quick-acting,a non-selective and killing green plant tissue on contact.Paraquat is widely used in more than 130 countries in the world,and it plays an important orle in agriculture.Form 70s,its high toxicity has been reported in animals as well as in human,and no specific antidotes,pulmonary toxicity is the main cause of death but damage to other organs has also been reported,such as liver,kidneys and heart. Once someone poisoned,the life will be in danger. Acute paraquat self-poisoning is a significant problem in the developing countries, especially in the parts of Asia,Ingestion of large amounts of paraquat could results in rapid death.Paraquat poisoning in the early phase could cause acute lung injury (ALI) or acute respiratory distress syndrome (ARDS).Patients usually die of multiple organ dysfunction syndrome(MODS)or respiratory failure.The poisioning pathogenesis is unclear, and no ideal therapy at present.Therefore,it was great important significance that the basic and clinical research of acute paraquat intoxication was strengthened.Objective To observe the content dynamic changes of paraquat in plasma and tissue in the paraquat poisoning rat model and explore the relationship between paraquat tissue content and organs injury.Methods All 90 adult healthy male Wistar rats were randomizedly divided into control group and paraquat poisoning groups.Paraquat in plasma and tissue were determined at different time points and at the same time the tissue of lung,kidney,liver,heart and brain were retained for pathological examination.The hydroxyproline of lung tissue was also determined.Results The concentrations of paraquat in rats blood were(525.69±98.91),(357.74±75.28),(69.44±17.22) ng/ml respectively at 8,24, 48 h after paraquat exposure,and disappeared at 3d. The contents of paraquat in lung tissue were (2170.85±452.33),(2769.18±596.17), (1351.90±158.60),(1054.03±87.47),(528.28±125.04)ng/g at 8,24,48 h,3d and 7 d after paraquat exposure respectively, disappeared at 14d.The contents of paraquat in kidney, liver and heart tissue respectively were(2391.54±400.78),(251.26±88.71), (330.95±62.09) ng/g at 8h,then reduced gradually. The paraquat in liver and heart tissue disappeared at 14d,and in kidney tissue at 28d. The contents of paraquat in brain were lowest,but it exist for longest time which were still detected in the brain tissue at 28d. The pathological changes were different in organic tissues,tissue injury was most serious and brain tissue injury was lightest.The injury of kidney, liver and heart were restored gradually,but the lung injury was aggravate gradually,which the content of lung hydroxyproline was increased at the same time(P＜0.05).Conclusions There were different paraquat content in different organs tissue and time points in paraquat poisoning rats.The more content of paraquat in the tissue,the more injury occurred,there could be relationship between paraquat tissue content and organs injury.The lung injury continued to develop after paraquat was completely eliminated in the rats.
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