EARLY ULTRASTRUCTURAL LESIONS OF DIPHENYLAMINE-INDUCED RENAL PAPILLARY NECROSIS IN SYRIAN-HAMSTERS

The ultrastructural lesions of diphenylamine-induced renal papillary n ecrosis in Syrian hamsters were characterized by transmission electron microscopy. Twenty-four male Syrian hamsters were orally administered 600 mg diphenylamine/kg body weight as a single dose. At 30 minutes a nd at 1, 2, 4, 8, 16 and 24 hours after administration of diphenylamin e, three hamsters were anesthetized with pentobarbital, perfused via t he left ventricle with half-strength KARNOVSKY's fixative, and the ren al papilla and outer medulla collected. Three hamsters administered 0. 5 ml peanut oil/kg body weight (vehicle controls) were anesthetized at 24 hours, perfused, and the renal papilla and outer medulla collected . Initial ultrastructural lesions were observed in the endothelial cel ls of the ascending vasa recta in the proximal portion of the renal pa pilla at I hour after dipenylamine administration. The endothelial cel l basal plasma membrane was elevated from the basal lamina, forming la rge subendothelial vacuoles. Alterations in inner medullary interstiti al cells, endothelial cells of the descending vasa recta, and the epit helial cells of the thin limbs of Henle and the medullary collecting t ubules were observed subsequent to the lesion in the ascending vasa re cta. It was concluded that the endothelial cell of the ascending vasa recta is the target cell in diphenylamine-induced renal papillary necr osis in Syrian hamsters.