ENHANCEMENT OF PAPILLARY NECROSIS AND CALCIFICATION IN THE RAT KIDNEY INDUCED BY ETHOXYQUIN OR RETINYL ACETATE

Abstract

Papillary necrosis associated with moderate to marked calcification in the renal papilla was incidentally observed in rats simultaneously or subsequently treated with two or more chemicals. In the gastric carcinogenesis model utilizing N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and NaCl as an 8-week-initiation treatment, the lesions in the renal papilla were selectively induced in rats subsequently administered 0.1% ehthoxyquin (EQ) in the diet for 32 weeks. EQ alone also induced the lesions, but the incidence and grade of the necrosis and calcification were much less than in the pretreated group. The additional experiment revealed that the combined pretreatment with MNNG and NaCl is important for induction of the lesions by EQ. In another experiment in which rats were simultaneously administered butylated hydroxyanisole (BHA) and retinyl acetate (RA) for 52 weeks, BHA enhanced the renal papillary lesions induced by RA. BHA alone did not induce the histopathological changes in the kidney. and the effect was dose-dependent for both BHA and RA.