Renal and pulmonary tumors in rats fed dimethylnitrosamine.

Abstract

SUMMARY Renal and pulmonary neoplasms developed in male and female Sprague-Dawley rats fed a diet containing 125 ppm dimethylnitrosamine (DMN) for longer than 80 days. The tumors found in the kidneys can be classified into two types: (a) benign solid and cystic adenomas occurring in rats fed DMN for less than 160 days; (o) anaplastic (possibly malignant) epithelial tumors in animals treated longer than 160days. Charac teristic nuclear alterations were observed in the cells of the proximal convoluted tubules and are interpreted as the earliest morphological manifestation in the kidney of DMN intoxication. Stimulated by the observation of the occur rence of two cases of cirrhosis of the liver among workers handling dimethylnitrosamine (DMN), Barnes and Magee (1) studied this compound in experimental animals, particularly in rats. These authors found that, when DMN was fed in a con centration of 50 ppm in a normal diet, primary liver neoplasms, seven of which showed mA©tastases, developed between 26 and 42 weeks in nineteen of twenty animals (11). Recently, the same authors reported the occurrence of renal tumors in a rela tively high incidence after feeding DMN to rats (12). During a study of precancerous changes in the liver, with the use of this compound, among others, multicentric tumors arising in kidneys and in lungs were observed before the findings of Magee and Barnes (12) were known. These obser vations are reported in confirmation of those of the latter authors.