Figure 2.

[³H]Adenosine uptake by hENT4: (a) PK15-NTD and PK15-hENT4 cells were incubated with 30 μM [³H]adenosine at ~22 °C for the specified times in the presence of the adenosine kinase inhibitor ABT-702 (50 nM) and the adenosine deaminase inhibitor EHNA (100 nM). *Significant difference in uptake by PK15-hENT4 cells at pH 6.0 versus pH 7.5 (Two way ANOVA with Tukey’s multiple comparison test, P < 0.05, n = 5). Note that there was no significant difference in uptake by the PK15-NTD cells at pH 6.0 versus pH 7.5. (b) hENT4-mediated uptake of [³H]adenosine was calculated from the data shown in Panel a as the difference in uptake between PK15-hENT4 and PK15-NTD cells at pH 6.0. For both Panels, data fit best to a one-phase association curve.