Urinary and serum mutagenicity studies with rats bearing experimental tumours.

Urine and serum samples of rats bearing three different experimental tumours (hepatocellular carcinoma, myelomonocytic leukemia and mesoblastic nephroma) were investigated for mutagenicity with the Ames Salmonella test. Enhancement of mutagenic activity in TA98 and TA100 was observed only in the case of urine samples obtained from animals bearing nephromas. Mutagenicity increased with increasing time after implantation of tumours. There was no coincidence between urinary and serum mutagenicity under the experimental conditions employed. Further studies are needed to determine the origins, and chemical and genotoxic characteristics of urinary mutagens. In addition, the question as to whether any mutagenic substances can be detected in fractions of plasma/serum should also be experimentally addressed.