Table 1.

Equilibrium dissociation constants of A1Rs and A2ARs expressed in HEK cells

TransfectionRadioligandDisplacerKD
A1R[3H]R-PIAR-PIA1.9 ± 0.4 nm
Caffeine90 ± 20 μm
A2AR[3H]CGS21680CGS21680110 ± 30 nm
Caffeine7 ± 1 μm
A1R + A2AR[3H]R-PIAR-PIA1.9 ± 0.3 nm
Caffeine93 ± 33 μm
[3H]CGS21680CGS21680120 ± 40 nm
Caffeine90 ± 20 μm*
A2AR + D2R[3H]CGS21680CGS21680110 ± 40 nm
Caffeine5 ± 2 μm
  • HEK cells were transfected with the indicated receptor. Membranes of these cells were incubated with [3H]R-PIA (0.8 nm) or [3H]CGS21680 (18 nm) in the absence or presence of increasing concentrations of displacer in 50 mm Tris-HCl containing 10 mm MgCl2 and 2 U/ml adenosine deaminase. Data represent means ± SEM.

  • *p < 0.001 with respect to both the KD value for A2AR in single-transfected cells and the KD value for A2AR plus D2R-cotransfected cells.