Table 1.

Specificity of [³H]NECA binding to A_2B adenosine receptors in control neutrophil membranes

	[3H]NECA Ki (μmol/l)
NECA	0.315 ± 0.028
2 Cl-adenosine	0.954 ± 0.600
R-PIA	1000 ± 86
SCH58261	>10
Teofilline	47 ± 3.5
MRS1706	0.005 ± 0.0003
DPCPX	2 ± 0.12
MRS1220	>10

Competition experiments were performed, incubating aliquots of neutrophil membranes with 20 nmol/l [³H]NECA (plus 50 nmol/l CPA and 100 nmol/l SCH₅₈₂₆₁) in the presence of increasing ligand concentrations. Ki values are expressed as mean ± SEM of three separate experiments. Ki values were calculated from IC₅₀ values (concentration of drug causing 50% inhibition of specific binding) using the Cheng and Prusoff equation.