CFUs kinetics observed in vivo by bromodeoxyuridine and near-UV light treatment.

Using continuous BrdUrd infusion in vivo and near-UV light irradiation in vitro, we have measured the time integrated S-phase fraction of CFUs derived from murine bone marrow. These measurements indicate a stochastic commitment to cycle of essentially the entire population of CFUs, consistent with the existence of a noncycling cell state G0. The data indicate that for B6D2F1 female mice the CFUs are committed to DNA synthesis approximately once every 52 h. Additionally, measurements of other CFUs parameters showed no significant effects of the BrdUrd infusion. Hydroxyurea challenges of BrdUrd-infused mice indicates that the capacity of the CFUs to respond to a proliferative stimulus during the infusion period is also unaffected by the BrdUrd.