Effects of CCNU on hematopoiesis in rats.

The effect of orally administered CCNU on proliferating and cytokinetically "resting" bone marrow cells was studied in rats. The resting bone marrow cells were selectively labeled with 3H-thymidine by the "complete 3H-thymidine labeling method." The results show a reduction in the number of absolute bone marrow cells to about 40% of the original value in 3 days. Regeneration was completed only after 22 days. No difference was found in the destructive or the regenerative pattern of CFU-C, myelopoietic, erythropoietic, lymphatic, or megakaryocytic cells. Resting and proliferating cells of the bone marrow were equally affected by CCNU.