Early ultrastructural lesions of diphenylamine-induced renal papillary necrosis in Syrian hamsters.

The ultrastructural lesions of diphenylamine-induced renal papillary necrosis 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 and at 1, 2, 4, 8, 16 and 24 hours after administration of diphenylamine, three hamsters were anesthetized with pentobarbital, perfused via the left ventricle with half-strength KARNOVSKY's fixative, and the renal 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 cells of the ascending vasa recta in the proximal portion of the renal papilla at 1 hour after diphenylamine administration. The endothelial cell basal plasma membrane was elevated from the basal lamina, forming large subendothelial vacuoles. Alterations in inner medullary interstitial cells, endothelial cells of the descending vasa recta, and the epithelial cells of the thin limbs of Henle and the medullary collecting tubules were observed subsequent to the lesion in the ascending vasa recta. It was concluded that the endothelial cell of the ascending vasa recta is the target cell in diphenylamine-induced renal papillary necrosis in Syrian hamsters.