Rats were injected with the herbicide, paraquat dichloride (25 mg/kg, i.p.), and their lungs were perfused 2-28 days later. Isolated lungs from rats treated with paraquat (PQ) 3 or 4 days before perfusion removed significantly less perfused 5-hydroxytryptamine (5-HT) than did saline-injected controls. This effect was not caused by PQ directly, since perfusion of lungs from untreated animals with PQ did not alter removal of co-perfused 5-HT. Monoamine oxidase activity of600 g supernatan fractions of homogenates of lungs from PQ-treated rats was also reduced compared to controls. Although removal of perfused angiotensin I (1 ng/ml) by isolated lungs was not altered by PQpretreatment, antgiotensin-converting enzyme activity in 600 g supernatant fractions of lung homogenates was reducedd significantly. These results suggest that PQ damages pulmonary endothelium and impairs the metabolic function of lung.
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Acknowledgements -We thank Ms. L. Dotzlaf. Mrs. 1. Mao and Mr. M. Winer for their technical assistance during this study and Ms. D. Hummel for typing the manuscript. This investigation was supported by Public Health Service Grant ES01861 from the National Institute of Environmental Health Sciences and HD02690 from the National Institute of Child Health and Human Development. R.H.A, was supported by NiH Training Grant GM07392.