Uptake of uridine by CLL cells in the presence and absence of dilazep and sodium. Freshly purified CLL cells were exposed to 10 μM ³H-uridine for the time periods indicated and uptake was measured in the following conditions: presence of extracellular sodium without dilazep (▪); presence of extracellular sodium with 100 μM dilazep (•); absence of extracellular sodium with 100 μM dilazep (○). Each point represents the mean ± SEM of a single representative experiment performed in triplicate. Error bars are not shown where smaller than the data point.