Factors affecting the sensitivity of rabbit lymphoid and bone marrow cells to Streptonigrin-induced chromosome...

In previous cytogenetic studies of rabbits injected with the clastogen, streptonigrin (SN), we observed a higher incidence of chromosome aberrations in lymph node cells than in marrow cells recovered 6 h after treatment. In this study we examined several factors that may be responsible for this difference in the incidence of lesions. Results from SN pulse-treated lymphoid and marrow cultures demonstrated that the responses were different in vitro also. In addition, at higher doses of SN, lymphoid cells displayed a greater sensitivity to the drug when treated during DNA synthesis; marrow cells showed no differences in sensitivity throughout the cell cycle. Analysis of the percentage of lymph node and marrow metaphases labeled following 2, 4, or 6 h of culture in the presence of tritiated thymidine indicated that G2 was less than 2 h in lymph node cells and approximately 4 hr in marrow cells. From these data we conclude that the difference in the incidence of lesions 6 hr after an in vivo SN exposure. However, our data also indicate that lymph node cells are innately more sensitive to the induction of lesions than are marrow cells.