FIG. 4.

Intracellular persistence of radioactive metabolites in CEM cells during incubation of 10⁶ cells with 2 μM (75 mCi/mmol) of [³H]AZT, [³H]D4T, or [³H]4′-Ed4T for 24 h. The cells were then washed and resuspended in fresh medium without nucleoside analogs at 0, 2, and 4 h after 24 h of incubation. The intracellular metabolites of each analog were determined by HPLC at 0, 2, 4, 8, 12, and 24 h. (A) The detected total radioactive metabolites were calculated as picomoles of each analog/10⁶ cells. (B) Concentrations of triphosphates formed. *, confidence limit of detection. Each value is the mean ± standard deviation from three independent experiments.