THE EFFECT OF I-125-5-IODO-2'-DEOXYURIDINE LABELING ON MURINE TUMOR-CELLS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 62  (1) , 22-26
Abstract
Labeling with 125IUdR [125I-5-iodo-2''-deoxyuridine] at radioactivity concentrations commonly employed in studies with i.v. injected tumor cells (1.0-0.1 .mu.Ci/ml) [for determining intravascular tumor cell survival] reduced considerably the in vitro reproductive viablility of mastocytoma tumor cells. Velocity sedimentation cell separation studies on mastocytoma cells that had been labeled for 12 h with 0.8 .mu.Ci/ml 125IUdR yielded a population that varied markedly between fractions with respect to distribution of label and, in parallel, with respect to induced loss of reproductive viability. A similar population of mastocytoma cells that had been labeled for 36 h with 0.01 .mu.Ci/ml 125IUdR yielded fractions where distribution of label was not associated with reduced reproductive viability. Although in vivo survival (as distinct from reproductive viability) of tumor cells injected i.v. and i.p. was not significantly altered within 7 and 30 h, respectively, by the commonly used concentrations of 125IUdR, it is suggested that in studies of the fate of injected tumor cells exponentially growing cells be labeled with 125IUdR for intervals well in excess of population doubling times at concentrations .ltoreq. 0.025 .mu.Ci/ml.