Local re-utilization of thymidine in normal mouse tissues as measured with iododeoxyuridine

• Published in: Cell and tissue kinetics Vol. 21; no. 6; p. 381
• Main Authors: Quackenbush, R C, Shields, A F
• Format: Journal Article
• Language: English
• Published: England 01.11.1988
• Subjects: Animals; Bone Marrow - metabolism; Bone Marrow Cells; Carbon Radioisotopes; Cell Division; Idoxuridine; Iodine Radioisotopes; Mice; Mice, Inbred BALB C; Spleen - cytology; Spleen - metabolism; Thymidine - metabolism; Thymus Gland - cytology; Thymus Gland - metabolism; Tritium
• ISSN: 0008-8730

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).