| Research Abstract |
Mitogenic stimulation by cell growth factor can increase the susceptibility to chemical carcinogenesis as seen in various organs and tissues. Therefore, we examined the influence of cell-proliferating stimuli on the incidence of carcinogen-induced CA and SCE. DMBA and NMU were given to L-E and S-D male rats at a dose of 50mg/kg body weight into a caudal vein. As hemopoietic stimuli, anemia and polycythemia were induced by removal of whole blood by cardiac puncture and transfusion with washed red blood cells. Chromosome specimens prepared from the femur bone marrow by standard method. BrdU was implanted subcutaneously in the abdomen 24 hours before the rats were killed. The control levels of CA and SCE were regarded as 0.09<plus-minus>0.03% and 5.80<plus-minus>s.37 per cell. In normal, anemic, polycythemic (PC) and PC+erythropoietin (EP 6 unit) rats at 6 hours, the incidence of CA induced by DMBA was 27.6<plus-minus>3.7, 45.3<plus-minus>5.7, 17.3<plus-minus>3.5 per cell respectively; of SCE, 9.11<plus-minus>2.47, 11.24<plus-minus>2.79, 6.87<plus-minus>2.47 and 12.03<plus-minus>3.70. NMU-induced CA incidence was 32.8<plus-minus>3.5, 55.6<plus-minus>4.3, 24.4<plus-minus>5.0 and 46.7<plus-minus>2.8; of SCE, 8.90<plus-minus>1.81, 18.63<plus-minus>3.12, 7.59<plus-minus>1.70 and 18.10<plus-minus>3.27. The intrachromosomal distribution of CA and SCE in various hemopoietic conditions were similar, accumulating along the 40% region of chromosome 1 and the 30% and 50% regions of chromosome 2. However, the peaks of CA and SCE were enhanced in anemia and suppressed in polycythemia. Thus DMBA-and NMU-induced CA and SCE depend on certain cell-proliferating stimuli and seem to be related phenomena. Liver cel
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