The effects of 5-iodo-2'-deoxyuridine upon the replication of ileal and spleen cells in vivo.

Studies were conducted on the replication of coexistent ileal cells and spleen lymphocytes, following the administration of sublethal amounts of 5-iodo-2'-deoxyuridine (1UdR). The antimetabolite was given s.c. to 3-week-old male Wistar strain rats in the following schedules: 1 ~tc IUdR-3H/gm body weight; 0.5 mg/kg t o m IUdR for 5 days followed by 1 /ac thymidine-3H (TdR-3H)/gm body weight; 150 mg/kg cold IUdR for 5 days followed by 1/ac TdR-3H/gm body weight. A control group received 1 /ac TdR-3H/gm body weight. Cell cycle patterns were determined from mitotic labeling curves. The results show that IUdR delays cells in DNA synthesis and in G2. It decreases the level of DNA synthesis, as evidenced by the reduced incorporation of T d R ) H per labeled cell and by the reduced percentage of labeled cells. The effects are dose-dependent. The changes induced by IUdR are similar to those previously reported from this laboratory in hepatocytes and in ileal cells following 2 and 10 /ac TdR-aH/gm body weight (J. Post and J. Hoffman, Radiation Res., 26: 422-441, 1965; J. Post and J. Hoffman, Radiation Res., 34: 570-582, 1968). Spleen lymphocytes are more sensitive to these changes than are ileal cells.