Acute Thrombus Formation in the Lungs of Phenylhydrazine-treated Rats

Abstract

We report pathological changes observed in the lungs of Phenylhydrazine (PHZ)-treated rats. Seven male SD rats were treated intraperitoneally with 50 mg/kg/day of PHZ for 3 days. PHZ-treated rats developed severe hemolytic anemia, and four out of the seven rats died after the final administration of PHZ; the three surviving rats were terminally sacrificed 24 hours after the final administration. Macroscopically, all lobes of the lungs of PHZ-treated rats were red or dark, and small white lesions were observed in the terminally sacrificed rats after fixation. Light microscopy revealed deposition of eosinophilic material in the alveolar septa of all PHZ-treated rats. This eosinophilic material was identified as fibrin (fibrin thrombus formation) in alveolar capillaries by immunohistochemistry and electron microscopy. This is the first report showing that PHZ induces acute thrombus formation in animals.