AN IN-VIVO MICRONUCLEUS ASSAY FOR DETECTING THE CLASTOGENIC EFFECT INRAT-KIDNEY CELLS

A micronucleus assay in vivo has been developed that is based on the u se of freshly isolated kidney cells from mononephrectomized rats. In t his validation study, a statistically significant increase in the freq uency of micronucleated cells was detected in rats given i.p. a single dose of four kidney carcinogens, N-nitrosodimethylamine, N-nitrosodie thylamine, N-ethyl-N-hydroxyethylnitrosamine and N-nitroso-N-methylure a. The clastogenic effect was more marked when the same dose was injec ted for 3 successive days. As compared to controls, treated rats displ ayed a reduction in the frequency of binucleated cells, presumably due to a toxicity-induced inhibition of cellular proliferation. The propo sed method should be suitable for the detection of the clastogenic eff ect of procarcinogens biotransformed into reactive species in the kidn ey.