SKCa Channels Blockage Increases the Expression of Adenosine A(2A) Receptor in Jurkat Human T Cells

Adenosine is a nucleoside displaying various biological effects via stimulation of four G-protein–coupled receptors, A(1), A(2A), A(2B), and A(3). Adenosine also modulates voltage-gated (Kv) and small conductance calcium-activated (SKCa) potassium channels. The effect of these potassium channels on the expression of adenosine receptors is poorly understood. We evaluated the action of BgK (a natural Kv channel blocker) and Lei-Dab7 (a synthetic SKCa channel blocker) on the expression of adenosine A(2A) receptors (A(2A)R) in Jurkat human T cells. We found that Lei-Dab7, but not BgK, increased the maximal binding value of the tritiated ligand ZM241385 to A(2A)R in a dose-dependent manner (+45% at 5 nM; +70% at 50 nM as compared to control). These results were further confirmed by Western blotting using a specific monoclonal antibody to human A(2A)R. The ligand affinity-related dissociation constant and A(2A)R mRNA amount were not significantly modified by either drug. We suggest that modulation of SKCa channels can influence membrane expression of A(2A)R and thus has a therapeutic potential.