Fig. 5.

Effect of the nonselective adenosine receptor antagonist 8-p-sulfophenyltheophylline (8-SPT) on adenosine (ADO)-induced inhibition of [¹⁴C]oxalate uptake by Caco2-BBE (C2) cells. C2 cells were preincubated with vehicle (Control) or 100 µM ADO for 2 min in the culture medium, and then [¹⁴C]oxalate uptake was measured as described in materials and methods. [¹⁴C]oxalate uptake was also measured in the presence of 8-SPT (100 µM) for 15 min followed by 100 µM ADO with continued presence of 8-SPT (ADO + 8-SPT) for 2 min, or 100 µM 8-SPT (8-SPT) alone for 17 min. Values are means ± SE of 5–6 independent experiments each of which was done in triplicate and was normalized to the respective Control value. 8-p-Sulfophenyltheophylline (8-SPT) completely and significantly blocked the inhibition induced by ADO (*P < 0.001 and < 0.01 for ADO compared with Control and ADO + 8-SPT, respectively, by ANOVA).