Local re-utilization of thymidine in normal mouse tissues as measured with iododeoxyuridine.
Thymidine (TdR) and its analogue, iododeoxyuridine (IdUdr), were used to quantitate nucleoside re-utilisation in vivo. Significantly different results obtained, however, depending upon what form of isotopically labelled iododeoxyuridine is used. No measurable local thymidine re-utilization was found in mouse thymus, spleen or bone marrow when the retention of [3H]IdUdR was compared with [14C]TdR. On the other hand, significant differences were found between the retention of [125I]IdUdR and [3H]IdUdR, which is attributed to de-iodination of iododeoxyuridine. Some thymidine re-utilization was found in duodenum using both [3H]IdUdR and [125I]IdUdR. Information on the in vivo distribution of TdR and the contention that a large degree of TdR re-utilization in the thymus is evidence of extensive cell death must be re-interpreted in the light of these results. In addition, evidence for little or no local re-utilization in some tissues will greatly simplify the use of [11C]TdR as an imaging agent for measuring tissue proliferation in vivo with positron emission tomography (PET).
Quackenbush
R C
RC
Fred Hutchinson Cancer Research Center, Seattle, WA.
Shields
A F
AF
D000818:Animals; D001853:Bone Marrow / Q000378:metabolism*; D001854:Bone Marrow Cells; D002250:Carbon Radioisotopes; D002455:Cell Division; D007065:Idoxuridine; D007457:Iodine Radioisotopes; D051379:Mice; D008807:Mice, Inbred BALB C; D013154:Spleen / Q000166:cytology / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism*; D014316:Tritium
D002250:Carbon Radioisotopes; D007457:Iodine Radioisotopes; D014316:Tritium; D007065:Idoxuridine; D013936:Thymidine