Modulation of N-nitrosodimethylamine kidney tumorigenesis by unilateral hydronephrosis and multiple putrescine administrations.

The effects of unilateral hydronephrosis by ligation of the right ureter and/or multiple injections of putrescine on kidney tumorigenesis by a single intrarenal injection of N-nitrosodimethylamine (DMN) were studied. Inbred female W rats in the unilateral hydronephrotic groups given or not given putrescine developed kidney tumors and/or neoplastic or preneoplastic lesions of the liver at an incidence of 55.6%. Almost all kidney tumors developed in the contralateral kidneys, which showed hypertrophy due to unilateral hydronephrosis. Rats having unilateral hydronephrosis and subjected to long-term putrescine administration after DMN injection frequently contracted large mesenchymal cell tumors (83%), whereas the group not given putrescine developed no mesenchymal cell tumors. Histologically, epithelial cell tumors showed a marked decrease in both gamma-glutamyltransferase activity and trypan blue uptake, but mesenchymal cell tumors did not.